Lithium energy storage device with composite anode

ABSTRACT

A Lithium energy storage device comprising a cathode, electrolyte, anode, and substrate. The materials contained in the anode and electrolyte region are electrochemically altered during initial formation and exposed to current cycles to create a lower impedance composite anode. The resulting composite anode bottom is a bi-layer comprising: i. a lithium metal layer and ii. a silicon-based interphase layer. The bi-layer acts as a barrier to inhibit Lithium ions from entering or leaving a Lithium saturated substrate, once the interphase surface is formed and the substrate is saturated with Lithium ions. This prevents cell failure from large volume changes/stresses during charge/discharge cycles and enables a significant decrease in cell impedance to enable better rechargeable cell performance.

BACKGROUND

The present invention relates to the field of semiconductor devices,more specifically to semiconductors used in energy storage devices.

The integration of energy storage devices, e.g. batteries, inmicroprocessor and memory chips is a significant requirement for the IoT(Internet of Things) devices and other applications. In addition to IoTapplications, emerging applications requiring these on-board nextgeneration energy storage devices include mobile devices; sensoryequipment; and autonomous environmental, biological, and socialfunctioning machines. Common examples of such functional devices aresmart dust and/or biomedical sensory/drug-delivery devices.Additionally, most or all solid-state energy storage devices willprogressively integrate lithium metal electrode material into itsoverall cell structure due to lithium metal's extremely high theoreticalspecific capacity (3860 mAh/g.)

Over the next generation, as human controlled and autonomous devicesincreasingly become miniaturized, total energy consumption requirementsfor electronic devices will decrease. Power consumption is expected tobe lower than 1 Watt for these devices. However, because of deviceminiaturization, the energy storage devices providing device power willneed to be miniaturized as well, sometimes be embedded in CMOS circuits,and will need high energy and power density.

Because of the pervasive use of miniaturized energy storage devices,e.g. batteries, there is a need for a silicon-based energy storagehousing unit with a structure that both protects and is protected fromthe external environment. Storage device design features are needed toenable the efficient mass fabrication of the entire miniature energystorage device via 3-dimensional features.

Additionally, there is an increasingly sharp demand for safe, wellcontained, all solid-state energy storage for microelectronic deviceswith the evolution of micro-electronics in the Internet of Things (IoT),like in the health care industries. The demand for all-solid statehigher gravimetric and areal capacity (area-normalized capacity) energystorage devices packed in smaller volumes and areas drives competitiveexploration of next generation materials, structures, designs, andmethods, especially via solid state microbatteries.

Conventional all-solid-state Li-ion batteries maintain control ofperformance via standard thin film encapsulation and packagingtechniques (e.g., 2.5D packaging-progressive layering methods.)Unfortunately, theoretically high capacity 3D (e.g. manufacturingprocesses using relatively larger volume components) thin filmmicrobatteries continue to fail commercially due to leakage, dielectricbreakdown, 3D fabrication failings, and parasitic cell degradation.Generally, 3D microbattery milestone failures, combined with cost, timeof assembly and large active/packaging areas (>1 mm²) of 2.5D formfactors, limit the commercial practicality of current microbatterydemand in an ever-shrinking foot print market.

SUMMARY

Some embodiments of the present inventions disclosed include thestructures, devices, and methods of making and use of energy storagedevices like lithium batteries and associated components andcombinations. Disclosed are novel materials and designs that provideconductive and/or adhesive improvements and containment enhancements inthe structures, methods, use, and operation of energy storage devices.Many of these embodiments have at least one electrode or anothercomponent made with a lithium metal and/or composition. Otherembodiments include all solid-state lithium batteries.

An embodiment of the present invention is a Lithium energy storagedevice comprising novel cathode, electrolyte, anode, and substratestructures, combinations and operations. The cathode is made of aLithium cathode composition, has an external cathode connection, and iscapable of producing Lithium ions. The electrolyte has an electrolytetop interface with the cathode and an electrolyte bottom interface withthe anode. A portion inside the full thickness of the electrolytecoverage contains a separator (dielectric) material which prevents theconduction of electrons through the electrolyte medium. The electrolytetop interface is electrically, chemically, and physically connected tothe cathode. A top of the anode (anode top) is electrically, chemically,and physically connected to the electrolyte bottom interface. The anodebottom is a bi-layer comprising: i. an interphase layer and ii. aLithium metal layer. The Lithium metal layer connects a novel anodecomposition to and through the interphase to surface of a solid siliconsubstrate with an external electrical connection.

Once the bi-layer (Li-metal with the interphase) is formed and thesubstrate is saturated with Lithium ions, the bi-layer acts as a barrierto inhibit Lithium ions from entering or leaving the Lithium saturatedsubstrate. This prevents failures from large volume changes/stresses ofthe substrate during charge/discharge cycles. The bi-layer contains andprotects the battery internals. The silicon substrate surrounding thebattery internals also contains and provides structural integrity bycontaining one or more of the battery components in a trench structure,partially bounded both by the bi-layer and the surrounding substrate.

Novel materials and methods are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a cross section elevation view of onepreferred novel structure of a Lithium ion battery prior togalvanostatic current cycling showing example precursors used to form anovel active region interface and other compositions and structures.

FIG. 2A is a post-mortem micro graph image of a cycled battery showingmaterials, layers, and interfaces at an active region interface within asubstrate (over the full trench width) resulting from no Lithiumcompound mixed within interfacial additive prior to galvanostaticcurrent cycling.

FIG. 2B is a magnified micro graph image of part of the anode interfaceregion in FIG. 2A.

FIG. 2C is a post-mortem micro graph image of a cycled battery showingmaterials, layers, and interfaces at an active region interface within asubstrate (over the full trench width) resulting from Lithium compoundmixed within interfacial additive prior to galvanostatic currentcycling.

FIG. 2D is a magnified micro graph image of part of the anode interfaceregion in FIG. 2C.

FIG. 2E is a diagram showing configuration of four microbatterieselectrically connected in parallel on a silicon wafer which is encasedin a coin cell.

FIG. 3 is a bar graph showing a comparison of charge transfer resistanceand interphase thickness and their respective resulting maximumdischarge capacity (above bar plots) in each of the embodiments of i.FIG. 2A and FIG. 2B and ii. FIG. 2C and FIG. 2D, respectively.

FIG. 4A is a Nyquist plot, between 1 MHz and 200 mHz and an appliedamplitude of 50 mV, of a single In-Silicon microbattery taken at 0current cycles and greater than 80 current cycles.

FIG. 4B is a diagram of an RC model for the 0 current cycle case.

FIG. 4C is a diagram of an RC model for the greater than 80 currentcycle case.

FIG. 5 is a magnified region illustrating the high and mid frequencyregions of the Nyquist plot shown in FIG. 4A.

FIG. 5A is a graph showing discharge capacity (in μAh/mm²) and theinitial voltage observed when applying current during discharge cycling(in volts) vs the respective electrochemically rechargeable cycle.

FIG. 6 is a micro graph image of a cross section and top down views of asolid polymer electrolyte (SPE) with a 10:1 ratio of Polycaprolactone(PCl) to Succinonitrile (SN) components saturating electrospunpolyacrylnitrile (PAN).

FIG. 6A is a scanning electron microscope (SEM) micro graph portion ofthe top region shown in FIG. 6 showing the polyacrylnitrile (PAN)component, without the integrated polymer electrolyte component, as afabric-like inter-woven layers of PAN material which is saturated withthe PCl/SN mixture.

FIG. 7A is a drawing of a symmetric electrochemical test device for asolid polymer electrolyte (SPE) with novel ratios of electrolytecomponents Polycaprolactone (PCl) and Succinonitrile (SN) symmetricabout polyacrylonitrile (PAN.)

FIG. 7B is a resistive/capacitive (RC) electrical model of an examplesolid polymer electrolyte (SPE) tested using the device in FIG. 7A.

FIG. 8 is a Nyquist plot of a symmetric electrochemical test devicecontaining solid polymer electrolyte (SPE) with a polyacrylnitrile (PAN)separator and a 10:1 ratio of PCI to SN.

FIG. 9 is a Nyquist plot of a symmetric electrochemical test devicecontaining solid polymer electrolyte (SPE) with a polyacrylnitrile (PAN)separator and 3:1 ratio of PCI to SN.

FIG. 10 is a Nyquist plot of a symmetric electrochemical test devicecontaining solid polymer electrolyte (SPE) with a polyacrylnitrile (PAN)separator and 2:1 ratio of PCI to SN.

FIG. 11 is a thickness vs ionic conductivity comparison of a solidpolymer electrolyte (SPE) measured as a function of polycaprolactone(PCl) to Succinonitrile (SN) ratios used in the polymer formulation ofthe electrolyte.

FIG. 11A is a micro graph image of a cross section of two layers of asolid polymer electrolyte (SPE) with a 10:1 ratio of Polycaprolactone(PCl) to Succinonitrile (SN) components saturating electrospunpolyacrylonitrile (PAN).

FIG. 11B is a micro graph image of a cross section of two layers of asolid polymer electrolyte (SPE) with a 3:1 ratio of Polycaprolactone(PCl) to Succinonitrile (SN) components saturating electrospunpolyacrylonitrile (PAN).

FIG. 11C is a micro graph image of a cross section of two layers of asolid polymer electrolyte (SPE) with a 2:1 ratio of Polycaprolactone(PCl) to Succinonitrile (SN) components saturating electrospunpolyacrylonitrile (PAN).

FIG. 12 is a flow chart showing a method of making an energy storagedevice having an anode in a 3D silicon trench substrate, a solid polymerelectrolyte (SPE) in and outside of the silicon trench substrate, and acathode material adhered to the SPE on the substrate field where allmaterials are encapsulated in a coin cell apparatus.

FIG. 13 is a flow chart showing an in-situ method of composite electrodefabrication using multiple stages of galvanostatic cycling of an energystorage device to fully form the novel active composite regioncontaining the solid polymer electrolyte (SPE), Silicon trench base,active anode material and active region interface precursors.

FIG. 14 is a block diagram of one preferred structure of the presentinvention after galvanostatic current cycling is applied showing a novelcomposite anode and novel composite electrolyte.

FIG. 15 is a composite micrograph showing various regions of the batterystructure in FIG. 14.

DETAILED DESCRIPTION

Among other things, compositions, structures, methods, devices, and usesare disclosed that affect the cross-linking and adhesion betweeninterfaces and material properties and function within an energy storagedevice. These features facilitate electron and ion-charge transferthroughout the electrochemical components of the energy storage devicesboth during formation of interfaces and materials and during generaloperation of the device.

Also considered are the physical and chemical conditions of howelectrochemically active energy storage components are synthesized;bonded together; and electrically, ionically, and physically isolated,particularly using 3D substrate and conformal layer depositionmanufacturing methods. These features also determine performancecapabilities within an effective energy storage device.

The independent treatment of component layers within an electrically andionically insulated energy storage housing unit can facilitate thefabrication, manufacture, operation, and use of highly efficient workingenergy storage devices. One preferred embodiment is the In-Silicon[trench] processing through control of physical parameters (e.g.,pressure and temperature). During fabrication, the physical and chemicalconditions of component layers are altered, especially regarding asolid/semi-solid electrolyte. Such independent treatment methods andresulting structures are disclosed in order to increase energy storagedevice functioning performance characteristics with special focus onimproving general energy/power density, lifecycle, internal resistancereduction, and interfacial chemical bonding.

Further, one preferred method to achieve high performing energy storagedevice components is to administer the synthesis and inter-materialbonding of energy storage device components during electrochemicalcycling of the completed energy storage device, e.g. in-situ compositematerial formation. The inter-layer bonding capabilities and resultingcharge-conductive/charge-transfer properties of the respective componentlayers can be optimized via controlled electrochemical conditions, priorto full cell cycling, where the in-situ induced chemical change tunes ahighly material-dependent and efficient solid state or semi-solid stateenergy storage device which enables high performance rechargeable ioncharge storage through strongly bonded, low-impedance internal layers.Such novel composite structures result in very low interfacial-inducedcharge-blocking resistance.

Because the prior art does not effectively synthesize and/orelectrochemically bond active energy storage components and/or make anduse improved compositions of matter, the following are some of thedeficiencies that exist in the prior art:

-   -   1. Reduced high-power density function or long energy delivery        (high energy density) capability.    -   2. Limited integration into single, small volume, low weight        special dimensions.    -   3. Limited to liquid electrolyte use—which has inherent safety        hazards (especially the organic components of liquid        electrolytes.)    -   4. Reduced durability and sustainability of        encapsulation/packaging (poor puncture resistance) or        degradation upon use, causing openings to outside environment        resulting in fires from Lithium exposure to oxygen.    -   5. Constrained processing methods for fabricating energy storage        active layers in an in-situ fashion at a device or assembly        level.    -   6. Failure to fabricate electrically/electrochemically active 3D        substrates which do not result in cell failure via dielectric        breakdown and/or inter-layer integration.    -   7. Failure to fabricate electrically/electrochemically active 3D        substrates which facilitate the integration of all solid-state        and/or semi solid-state energy storage device components.    -   8. Failure to fabricate electrically/electrochemically active 3D        substrates which facilitate the integration of all solid-state        and/or semi solid-state energy storage device components using        slurry and casting type deposition methods.    -   9. Failure to create composite active materials in an energy        storage device residing within the substrate of a        microelectronic device.    -   10. Failure to create composite active materials in an energy        storage device residing within the substrate of a        microelectronic device, where the composite active material        created in the energy storage device includes or incorporates        the microelectronic device substrate.    -   11. Failure to incorporate crystalline silicon as active        electrode material in a Lithium based energy storage device,        without the incorporation of carbon conductive additive        materials mixed with crystalline silicon in a homogenous        fashion. The prior art also has well documented short comings        specifically related to lithium metal electrode and/or Lithium        compound containing-based energy storage devices, such as:        -   i. Incomplete or lack of Lithium metal spatial control when            the device use is underway.        -   ii. Unsaturated Lithium metal interface between electrode            and electrode-contact materials.        -   iii. Ineffective electrode substrates or treated electrode            surfaces which enable lithium metal adsorption/desorption            reduced stresses and/or suppress lithium metal dendrite            formation.        -   iv. Ineffective electrode substrates or treated electrode            surfaces (e.g. Silicon) which allow for suitable nucleation            or Lithium hosting sites, thereby limiting the performance            of the Lithium/electrode material created in-situ and            typically leading to cell failure (e.g. dendritic growth of            Lithium metal).        -   v. Ineffective use of crystalline 2D and/or crystalline 3D            silicon material as an energy storage device electrical            contact for electrode materials.        -   vi. Ineffective use of crystalline 2D and/or crystalline 3D            silicon material as an energy storage device electrical            contact for electrode materials and for use as sustainable,            Li-charge hosting composite anode material.

Energy storage devices with all solid-state components also have welldocumented drawbacks primarily in their ability to:

-   -   1. Maintain low interfacial resistance between independent        active energy storage/energy mobile layers as well as electrical        contacts of the electrode materials, especially after multiple        electrochemical charge and discharge cycles.    -   2. Improve interfacial impedance (decrease cell impedance)        between independent active energy storage/energy mobile layers        as well as electrical contacts of the electrode materials,        especially after multiple electrochemical charge and discharge        cycles.    -   3. Create thick cathode materials with low internal resistance,        as well as low interfacial impedance, and/or significantly        control or mitigate electrochemically accessible surface area of        cathode materials viable for high capacity and high power        efficient rechargeable cycling.    -   4. Maintain electrochemically (e.g., ionically, electronically)        labile interfaces between electrolyte and electrode and        electrode contact materials due to insufficient chemical bonding        and/or interlayer adhesion at the electrolyte/electrode and        electrode/electrode contact interfaces. Lability in the        definition used above refers to the layer or interfacial        material (per unit area, volume, density, etc.) having high        ability (long electrochemical lifetime) of being ionically        and/or electronically conductive.

There is a need to improve the structural and chemical bonding ofelectrochemically active energy storage components to enable morecompactly adhered and stable structures with higher energy storingcapacity and power delivery per unit volume, area and/or mass, reduceddevice internal resistance (particularly at material interfaces),increased durability, extended cycling lifetime and reduced leakage.Interfacial media used in electrochemical energy sources ormicroelectronic devices can extend the lifetime and average orperformance capabilities (e.g., power/rate capabilities, translationalmobility of charge, average area of high functioning charge-conductiveand/or host-capable material, etc.)

These issues are addressed in part using a novel silicon-basedencapsulation and packaging in conjunction with composite silicon-basedelectrode material. Methods are disclosed to fabricate novel materialsand conformally deposited all-solid-state Li-ion materials into 3Dtrench patterned silicon substrates, using advanced solid polymerelectrolyte (SPE), using interfacial additives (e.g. LiTFSI containingPolyaniline (PAM)) combined with commercially available batterymaterials (e.g., graphite and Lithium Iron Phosphate (LFP)).

Illustrative embodiments of these inventions may be described herein inthe context of illustrative methods for forming energy storage devices,along with illustrative apparatus, systems and devices formed using suchmethods. However, it is to be understood that embodiments of theinvention are not limited to the illustrative methods, apparatus,systems and devices but instead are more broadly applicable to othersuitable methods, apparatus, systems and devices.

It is to be further understood that the present disclosure will bedescribed in terms of a given illustrative architecture; however, otherarchitectures, structures, substrate materials and process features andsteps may be varied within the scope of the present disclosure.

It will also be understood that when an element such as a layer, regionor substrate is referred to as being “on” or “over” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being “directlyon” or “directly over” another element, there are no interveningelements present. It will also be understood that when an element isreferred to as being “connected” or “coupled” to another element, it canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well as any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

Features with the same reference number in different Figures perform thesame function and have the same description unless the description ismodified in a later Figure.

FIG. 1 is a block diagram of a cross section elevation view of onepreferred novel structure of a Lithium ion battery 100 prior togalvanostaic current cycling showing example precursors and structuresused to form of a novel active region 190 interface, a novel compositeanode, a novel electrolyte, and other compositions and structures.

A preferred embodiment of the energy storage device 100 comprises asilicon substrate 160 comprising at least one trench 150 (one or moretrenches 150) disposed therein. The (at least one) trench 150 providesan energy storage device containment feature with chemical, ionic, andelectronic conductive access to a formed active region interface 120 and190 (including the region created with a LiTFSI/PANI/graphite mixture ina preferred embodiment), a transition region (or layer) 172 (refer toFIG. 2D), and anode 175. After current cycling, in a preferredembodiment the anode 175 becomes a composite anode 175A which can beviewed as containing lithiated crystalline silicon 160A, a silicon-basedinterphase layer 230, the lithium metal layer 240, and the transitionlayer 172 which further includes a Lithium salt (LiTFSI), PANI,graphite, and electrolyte materials. (Here the bi-layer is thesilicon-based interphase 230 and the lithium metal layer 240 whichmaintains a desired mobility control of Lithium ions.) In addition,during the current cycling and the formation of the bi-layer, thesubstrate 160 becomes a lithiated substrate 160A.

In some embodiments one or more insulation layers (154, 156) cover thesides of the trench 150. The trench 150 or the trench in combinationwith the insulation layers (154, 156) create a 3D space in which anelectrode 175 (e.g. an anode 175) is deposited. In some embodiments alayer 170S is disposed between the anode 175 and the insulation layer(s)(154 or 156.)

In one preferred embodiment of such energy storage housing thecomponents are created by implementing three-dimensional (3D)space/volume cavities, micro-cavities, channels, or trenches 150typically through etching, pressure, or otherwise destructive methodsimplemented onto/into two-dimensional (2D) substrates 150 such assilicon. The beneficial aspects of implementing energy storage housingdevices into such semiconductor-type materials as silicon are paramountfor the integration of power devices into commercially-ubiquitousstarting substrates of technologically smarter, more autonomous andcapable functioning devices. The need for the standardization of energystorage housing devices that can be commercially utilized for thestorage of both thin film (relatively lower capacity/higher powerdensity capability) and thicker films, layers, or components (relativelyhigher capacity/lower power density capability) is critical in thecommercial development of micro-power and micro-battery capabilities.

The substrate 160, in one embodiment, may be made from a base material160 such as a non-porous silicon (Si)-based substrate, a single-crystalnon-porous Si substrate, crystalline silicon, a low resistance doped(e.g., Boron-doped) crystalline silicon material, and a partially porouscrystalline silicon material and/or the like. The doped crystallinesilicon material is doped with Boron at a concentration of approximately10¹⁹ cm⁻³. In one example, the substrate 160 may have a verticalthickness ranging from 5 μm to 1000 μm although other thicknesses areapplicable as well. The horizontal width of the substrate 160 may varybased on a number of energy storage devices (in trenches 150) that areto be formed. A first set of trenches 150 may be formed on the top sideof the substrate 160 and a second set of trenches 150 may be formed onthe bottom-side of the substrate (not shown.) The trenches 150 may beformed utilizing etching, such as deep reactive-ion etching (D-RIE), orwet etching methods utilizing chemicals such as hydrofluoric acid, orany other standard technique. More generally, any top-down method may beused to create the trenches 150 by etching or removing a desired amountof the silicon substrate 160. In one embodiment, the second set oftrenches 150 are formed by flipping the substrate over on a substrateholder and then performing the patterned etching process(es).

For instance, 3D features (≤1 mm²) in crystalline silicon substrates arecreated via standard microfabrication methods (e.g. through silicon via(TSV) reactive ion etching (RIE)). For example, 16 trenches (1 mm² area,350 μm depth, at a 2 mm pitch) enabled manufacture of multiple 35 mm×35mm chiplets on a 200 mm wafer.

The substrate 160 has a top surface 161 and a bottom surface 162.

In preferred embodiments, the trenches 150 may have a horizontal width(201 in FIG. 2A) with a trench bottom area 115. The width 201 rangesfrom less than 5 μm to greater than 1 mm, and a vertical thickness orheight ranging from less than 5 μm to greater than 400 μm, althoughother dimensions are applicable as well. In some embodiments, the trenchdepth does not exceed approximately ¾ of the thickness of the substrate160. The trenches may be rectangular, circular, etc. as determined withthe required shape of the desired form factor. The second set oftrenches 150 are optional and can have similar dimensions and shape orcan be different in dimensionality and/or used differently.

The trenches 150 have a trench bottom (shown in FIG. 2), one or moretrench sides (typically 157), a trench depth, and a trench opening atthe top of the trench 150 with a trench opening area. The trench bottomhas a trench bottom area 115 of the trench that interfaces with thesubstrate 160 at the trench bottom. The trench 150 sides (typically 157)are shown as the vertical surfaces of the trench 150 in FIG. 1, thetrench opening opens through the substrate 160 top surface as shown inFIG. 1. The trench 150 depth is measured from the substrate 160 top 161to the trench bottom. A trench cavity 158 is defined by the trenchbottom and trench sides 157 and/or the material (154, 156, andoptionally 170S) deposited on the trench bottom 170B and trench sides157. Locations of these components is evident from inspection of FIGS. 1and 2 of this description where some reference numbers may be omittedfor clarity.

In some preferred embodiments, the trench 150 sides 157 are covered withone or more insulating layers (154, 156.) The insulating layers (154,156) provide further containment for the battery electrode (e.g., anode)175 contained in the trench cavity 158 and prevent external contaminantsfrom entering the cavity 158 or internal components from leaking out tothe external environment. Additionally, the insulating layerseffectively control the directionality and isolation of ion movementthroughout the energy storage device—which enables a less resistive,better performing energy storage capability. The opening (patterning) ofinsulating layer(s) enables spatial control of electrical contactbetween ion-containing energy storage device components (e.g., anode orcomposite anode) and the electron-providing substrate (e.g., silicon).Such patterning capability enhances performance through control ofelectrode/contact area and high suppression of leakage within the energystorage device.

In some preferred embodiments, one or more of the insulating layers(154T, 156T) also covers the substrate top external to the trenchopening. These layers (154T, 156T) provide addition isolation of thedevice 100 internal components and provide an electrical insulationbarrier to the components above them.

In some preferred embodiments, there is a single insulating layer 154 onthe trench sides and/or the substrate 160 top 161. In other preferredembodiments, there are one or more additional insulating layers (154,156) on the trench sides (157) and/or the substrate 160 top 161. Theinsulating layers are made of electrically and/or ionic-insulatingmaterial that have structure strength and the ability to contain, e.g.prevent the penetration of, and act as a barrier against reactivematerials like Lithium, Lithium ions, electrons, etc. Preferredmaterials for the insulation layers (154, 156, and optionally 154T and156T) include: silicon dioxide (SiO₂), SiO₂ and silicon nitride (Si₃N₄)combinations, Si₃N₄., etc.

In preferred embodiments, the total thickness of the insulating layers(154, 156) is between 200 nm and 500 nm. Other ranges possible for totalthickness of the insulating layers can be less than 50 nm or greaterthan 700 nm. The insulating layers (154, 156) are deposited by any oneor more of the following: physical vapor deposition (PVD), chemicalvapor depositions (CVD), atomic layer deposition (ADL), etc. Depositiontreatment such as annealing can be utilized to modulate the physicalresulting properties of the insulation layer(s) (e.g., hardness,adhesion, etc.)

The selection and/or deposition ordering of the insulating layers (154,156) can depend on the desired properties for the final layeredstructure and include properties like: electrical insulation, adhesion,material strength, ion, electron penetration susceptibility, mechanicalpenetration strength, and directionally based strength of chemicaland/or ionic containment, isolation and translational motion.

In preferred embodiments of the device 100 there are no insulatinglayers (154, 156) or any other material on the trench 150 bottom ordesired portions of the trench 150 bottom. This is to enable electriccontact between the active region interface 190 (and to the anode 175)and the substrate 160 using novel materials and methods as describedbelow.

In one embodiment, the field, sidewalls and base of the 3D trenches wereconformally patterned with electron/ion insulating materials (e.g., SiO₂and/or Si₃N₄). In one embodiment, insulation was partially etched awayat trench bases to create an electrical connection between the activebattery material and silicon substrate utilized during formation of theactive layer and general battery operation. In a preferred embodiment, aconductive polymer adhesive mixed with a Lithium containing compound isplaced on the trench bottom and heat treated. In preferred embodiments,active battery material slurries (e.g., graphite, polymer electrolyte,interfacial additives) filled the insulated trenches, were pressed,heated, and dried—yielding well adhered silicon encapsulated batterycells. In preferred embodiments, the top of the trench was subsequentlycovered in polymer electrolyte saturated polyacrylnitrile (PAN)separator material and was then planarized with a metal contactlaminated cathode material (Lithium Iron Phosphate—LFP) via conductiveepoxy. The In-silicon energy storage devices were then diced to obtainthe desired number of parallel microbatteries and total footprint.Finished In-silicon microbattery cell(s) were encapsulated with coincell materials. More description of methods of making are providedbelow.

In a preferred embodiment, a novel conductive polymer adhesive layer(170, 170B) is disposed on the substrate 160 on the trench bottom area115 covering the entire (active) area 120 of the trench bottom. Theconductive polymer adhesive layer (170, 170S) may optionally be disposedover the insulating layers (154, 156) on the trench sides depending onthe method of manufacturing and/or other design choices.

In preferred embodiments, the thickness of the conductive adhesivemixture (170, 170B) layer on the trench bottom is between 20 nm and 10μm when initially deposited and integrated with the full energy storagedevice. However, other thicknesses are possible outside the rangespecified. A preferred thickness range is between 30 nm and 500 nm. Theadhesive mixture (170, 170B) is in direct physical, chemical, electriccontact with the substrate 160 at the active area 120 of the trenchbottom.

(Note that the thickness of the deposited Li-containing PANI layer (170,170B) may decrease once the cell is electrochemically cycled (pre-cycletreatment). Thickness decreases may be up to or greater than 75% of theinitial PANI layer (this is comparing pure PANI layer in initial fullcell vs the pure (non-composite integrated PANI) layer in post-cycledfull cell.)

The thickness of the optional conductive adhesive mixture (170, 170S)layer on the trench side is between 20 nm and 10 μm, with a preferredthickness embodiment of 5 nm and 500 nm. However other thicknessesoutside of this range are possible.

The conductive adhesive mixture layers 170 are deposited by any one ormore of the following: polymer casting, hot casting, spin coating, microor nanopipette deposition, pressurized micro or nanopipette deposition,doctor blading, hot blading or any method which sufficiently depositsthe polymer based conductive adhesive at the desired trench or substratelocations.

The conductive adhesive mixture (170, 170S, 170B) is transformed in itsphysical and chemical properties through an annealing step afterdeposition on/in the substrate. The anneal step, among other changes,alters the chemical adhesion and inter/intra chemical cross-linking ofthe PANI material—thereby advancing the conductivity, structuralintegrity and adhesion of the adhesive mixture as well as the adhesivemixture/Silicon interface 170B.

The conductive adhesive mixture (170B) is transformed by novel methodsto create a novel active region interface 190 partially circled 190 inFIG. 1 and explained in more detail in FIGS. 2 and 14.

In preferred embodiments, the trench 150 cavity 158 is structurallydefined by the transformed adhesive mixture (170, 170B) on the trenchactive area 120 and either the adhesive mixture layers (170, 170S) orthe insulating layers (154, 156) on the trench 150 sides. In a preferredembodiment, the trench cavity 158 is filled with a 3D volume of astorage device electrode, e.g. anode 175 material. In another preferredembodiment, the trench cavity 158 is filled with a 3D volume of astorage device electrode, e.g. anode 175 material followed by polymerelectrolyte material 130B which extends above and below the top plane ofthe 3D trench.

The substrate 160 material on three sides of the trench 150, theinsulating layers (154, 156), optionally the adhesive mixture (170S)transformed on the sides, and the transformed adhesive mixture 170B onthe bottom active area 120, creates a strong electrical, chemical, andphysical contact of active energy storage device materials andelectrical contacts as well as provides an excellent containmentstructure for the anode 175 and the active region interface 190.

In addition, once formed the bi-layer (230, 240) form a containmentbarrier at the trench bottom area 115 which promotes the mechanical andstructural integrity, and therefore the resistance-dependentcharge-storage performance capability, of the Li-active silicon materialresiding below the trench bottom as Lithium material is mobilized intoor out of the silicon material during reversible electrochemicalcycling.

In preferred embodiments, the electrode/anode 175 is made of any anodicmaterial including: graphite, lithiated graphite, carbon and lithiumbased mixtures, lithium metal, lithium powder, lithium powder and/orlithium composite material saturated in conductive adhesive mixture 170,lithium titanate material (LTO), silicon, crystalline silicon,silicon/carbon composite material, silicon/carbon/additive compositematerial, lithium powder/carbon/solid electrolyte composite, or anyother suitable Li-charge hosting anode material(s.)

The electrode/anode 175 is deposited using known techniques and methodsincluding: wet material deposition (e.g., slurry deposition via nano ormicropipette, slurry casting, doctor blading, spin coating or any othersuitable method of depositing “wet” active electrode materials) or drymaterial deposition (e.g., Vacuum deposition techniques such as physicalvapor deposition, atomic layer deposition, chemical vapor deposition,etc.). In a preferred embodiment, the electrode/anode 175 fills theentire available volume in the trench cavity. In another preferredembodiment, the electrode/anode 175 fills nearly the entire availablevolume in the trench cavity, with the polymer electrolyte materialfilling the top-most portion of the trench cavity. In yet anotherpreferred embodiment, the entire cavity is filled with all active energystorage device components (anode, electrolyte, separator (if needed),cathode, electrical contacts and interfacial additive materials).

The anode 175 has an anode bottom 174 (in FIG. 2A) interfacing throughthe adhesive mixture (170, 170B) at the bottom of the trench and withinthe substrate 160. The anode 175 has an anode top that, in preferredembodiments is coplanar with the top of the insulating layers (154T,156T) on the substrate top 161 (or the substrate top 161, if noinsulating layers) but having a top anode surface uninsulated and ableto electrically connect to electrolyte layers 130. An additionalpreferred embodiment has the anode 175 with an anode top nearly coplanarwith the top of the insulating layers (154T, 156T) on the substrate top161 (or the substrate top 161, if no insulating layers) but having a topanode surface uninsulated and able to electrically connect toelectrolyte layers 130, where the electrolyte layers 130 extend into thetrench, beyond (into) the top plane of the substrate top 161, with theelectrolyte layer being coplanar with the top of the insulting layers(154T, 156T) on the substrate top 161 (or the substrate top 161, if noinsulating layers). The anode bottom 174 is physically, electrically,and chemically attached to and integrated with the substrate 160 afterthe active region interface 190 is formed. During formation of theactive region 190 ions are allowed to pass between the anode bottom 174and the substrate 160 to lithiate the substrate 160A. The novelformation and composition of the active region 190 at the anode bottom174 lowers of the interfacial impedance of the electrochemically workingcell, as described below.

An electrolyte 138, e.g. a Solid Polymer Electrolyte (SPE) 138 initiallyhaving one or more electrolyte layers is placed on top of the topinsulating layers (154T, 156T) and in physical and chemical connectionto anode material 175 residing below it, in some embodiments. Inalternative embodiments, the electrolyte can be placed over thesubstrate top 161 and the anode 175 top 176 or on the anode 175 materialin the trench 150, while enabling the anode and electrolyte material tomaintain close physical and chemical contact contributing to the highelectrochemical performance capability observed in the currentinvention. The electrolyte 138 bottom 134 is physically and chemicallyattached and connected to the anode top 176. However, the electrospunpolyacrylnitrile (PAN) separator 135 (in a preferred embodiment) enableselectrical insulation between the anode or anode/electrolyte compositematerials and the cathode or cathode/electrolyte composite materials andis saturated and surrounded on all sides by the Li-conductive polymerelectrolyte. After current cycling (galvanostatic cell cycling) thecomposition and interface of the solid polymer electrolyte changes asdescribed below.

Initially, in some preferred embodiments, the electrolyte 138 has one ormore electrolyte components or layers (130B, 135, 120T). In preferredembodiments, the electrolyte 138 can be any known electrolyte materialknown in the prior art that is compatible with other materials in thedevice 100, including but not limited to liquid, semi-solid andsolid-state electrolyte materials. (Note that in this disclosure theelectrolyte 138 is sometimes referred to as a Solid Polymer Electrolyte(SPE) 138. This reference specifically applies to solid-state polymerelectrolytes, but at times can be used to describe any solid-stateelectrolyte without loss of generality.)

In one preferred embodiment shown in FIG. 1, the electrolyte 138comprises top 130T and bottom 130B layers 130 of a Lithium compound,e.g. a Lithium salt containing polymer compound immersed in a separatorlayer 135 of polyacrylnitrile (PAN) which provides electrical insulationbetween anode and cathode cell components. In preferred embodiments, theLithium salt compound 130 is Lithium bis(trifluoromethanesulfonyl)imide(LiTFSi) salt electrolyte. Other materials 130 could be used includingbut not limited to lithium hexafluorophosphate, lithium perchlorate,lithium phosphate compounds, lithium bromide compounds, etc.

Initially, the electrolyte 138 has a thickness between 28 μm and 82 μm.However, thicknesses below or above this range are possible. They can bedeposited by any of the following methods: polymer casting followed byPAN deposition and subsequent polymer casting or PAN lamination,calendaring, or adhesion to the top surface of electrode material (e.g.,anode 175 or cathode 180) followed by deposition of polymer electrolyteonto the opposing electrode material and subsequent immersion ofPAN-attached electrode material or through independent fabrication ofthe polymer/PAN/polymer material 138 with suitable trench-fittingdimensions followed by deposition of the electrolyte 138 into the trenchand in contact with the bottom electrode already residing in the trenchfollowed by heat treatment between 30 C and 80 C, however othertemperatures are possible below and above this range.

In preferred embodiments note that there are not defined thicknesses forthe “top” or “bottom” polymer electrolyte materials. These materialssaturate the fiber-woven PAN such that polymer material is coatingeverything in and above and below the PAN. In these embodiments thethickness of polymer above and below the PAN is undetermined. Instead,we should characterize the thickness as the entire thickness of theelectrolyte 138. “Top” or “bottom” may be used to describe where theelectrolyte 138 interfaces with other battery components, e.g. thecathode 180 and anode 175.

The middle layer 135 can be made of any of the following materials:polyacrylnitrile (PAN), polyethylene, polypropylene, and any combinationof suitable mixtures (e.g., polyethylene-polypropylene.)

Again, the composition and interfaces of the electrolyte 138 changeafter the current cycling (galvanostatic cell cycling) as describedbelow.

A cathode, e.g. layers 180 and 185, with a cathode bottom 181 and acathode top 186, is disposed on the top 136 of the electrolyte 138. Thecathode bottom 181 is physically, electrically, and chemically attachedto the electrolyte top 136.

The cathode (180, 185) can comprise any known cathode material (Lithiumcathode composition) and structure known in the art as long as thecathode is electrochemically compatible with other components of thedevice 100.

In a preferred embodiment, the cathode (180, 185) comprises a conductivelayer 185 with a Lithium compound layer 180. In preferred embodiments,the cathode Lithium compound layer 180 is Lithium Iron Phosphate (LFP)with a preferred layer thickness between 15 μm and 45 μm. A preferredconductive layer 185 comprises aluminum or an aluminum-based alloy 185with a thickness between 8 μm and 50 μm. It should be known that otherthicknesses of both Lithium Compound layer 180 and conductive layer 185are possible. Other materials for the Lithium compound layer 180include: Lithium Cobalt Oxide (LCO), lithium manganese oxide (LiMn2O4)(LMO), Lithium Manganese Oxyflouride (Li2MnO2F), lithium nickelmanganese cobalt oxide (LiNiMnCoO2) (NMC), lithium manganese nickeloxide (LiMn1.5Ni0.5O4), lithium iron phosphate (LiFePO4), lithium ironmanganese phosphate (LiFeMnPO4), lithium nickel cobalt aluminum oxide(LiNiCoAlO2) (NCA), carbon-substrate based catholytes, carbon/siliconcomposite catholytes, or any other cathode type material which iselectrochemically and mechanically compatible with the energy storagedevice 100 presented herein. Other materials for the cathode conductivelayer 185 include: nickel, titanium, aluminum alloys, etc.

The cathode layers (180, 185) can be deposited using known techniquesincluding: wet material deposition (e.g., slurry deposition via nano ormicropipette, slurry casting, doctor blading, or any other suitablemethod of depositing “wet” active electrode materials) with some form oflaminating/pressure-roller/binding process which enables intimate, lowresistance contact between the two cathode layer (180, 185) or drymaterial deposition (e.g., Vacuum deposition techniques such as physicalvapor deposition, atomic layer deposition, chemical vapor deposition,etc.) of one cathode layer 180 onto the other 185.

Further environmental isolation, containment and integrity for intimatebattery layer contact of the device 100 is provided by casing structures(192, 194.) For example, a stainless-steel top coin cell casing 192 isattached 198 to the top of the device 100 making electrical contact withthe cathode conductive layer 185. A stainless-steel bottom coin cell 194casing is attached 199 to the bottom of the device 100 making electricalcontact with the substrate 160 bottom 162 and optionally, the sides ofthe substrate.

It should be noted that any number of electrically conductive (e.g.,Aluminum and/or stainless steel) metal spacers or springs can beutilized to maintain constant mechanical pressure throughout theIn-Silicon coin cell. The casings (192, 194) are physically andelectrically attached to their respective components in the device 100,including the spacer components, and provide further structure integrityand isolation and containment barriers for the device 100. Additionally,the casings (192, 194), the backside of the substrate 162 or thespacer/spring components can be physically and electrically, as well aschemically attached to their respective components in the device 100through the use of a conductive adhesive material such as silver epoxy,silver adhesive paste or other conductive/adhesive promoting materials.

The casings (192, 194) are physically and electrically attached to theirrespective components in the device 100 and provide further structureintegrity and isolation and containment barriers for the device 100.Additionally, the casings (192, 194) can be physically and electrically,as well as chemically attached, to their respective components in thedevice 100 through the use of a conductive adhesive material such assilver epoxy or silver adhesive paste.

Referring to FIG. 2A, a micro graph image 200 showing materials, layers,and interfaces at an anode interface region 190 over the full horizontalwidth 201 of the trench 150. Initially, an adhesive, e.g. PANI, wasplaced between the substrate 160 and the anode bottom 174. The adhesivehad no Lithium compound mixed in. After the structure 100 was completed,current was forced through the battery (galvanostatic cell cycling),cycling between a lower and a higher cell voltage as well as lower andhigher applied current. During this cycling operation, the active regioninterface 190 is formed.

Note that FIGS. 2A, 2B, 2C, and 2D show the respective active regioninterfaces 190 after the galvanostatic cycling was completed. It isbelieved that the active region interfaces 190 were formed within thefirst 1 to 20 galvanostatic-controlled cycles of the full energy storagedevice. Once formed the active region interface structure laststhroughout the battery's higher performance lifetime and the structuremay change or degrade upon capacity fade of the battery device.

The active region interface 190 shown in each of these figures can be aregion 190 of one of multiple parallel microbatteries made on onesubstrate 160 as shown 295 in FIG. 2E. It should be known that a singlemicrobattery can be made on a single substrate 160 and encased in thesame manner as displayed in FIG. 2E. In this embodiment, the fourmicrobatteries 295 were connected in parallel electrically before incased 296 to make the final battery 297.

The micro graphs 200, 225, 250, and 275 were taken at battery life end.

FIG. 2B is a magnified 210 micro graph image 225 of part of the anoderegion interface 190 pertaining to the silicon/PANI/Graphite materialsinterface, shown in FIG. 2A within the dashed box region. FIG. 2Breveals that the active region interface 190 is a complex region withseveral layers. From bottom up, there is the silicon base or substrate160, an electrically polarized base of the trench or trench bottom (morespecifically the bottom component of the electrically polarized siliconarea 173 of the bi-layer 230, 240), an electrically polarized,Silicon-based interphase layer 230 which is also part of the trenchbottom and, a small non-smooth layer 235, (235 is possibly PANI that, inthis embodiment, does contain Lithium metal or Lithium salt—hencecreating a poor-Li-conduction layer and preventing mobile transport ofLi⁺ during current cycling. Consequently, this results in poor adhesionof the in-situ formed, Lithium metal layer 240—where poor adhesionbetween the in-situ formed Li-metal layer 240 and Silicon-basedinterphase layer 230 (the in-situ created bi-layer 230, 240) increasesinterfacial impedance during charge transport of the system—forexamples, in transporting Li+ through the layer of adhesive, PANI 245,and the graphite anode 175 or electrical charge through the crystallinesilicon substrate material 160—thereby resulting in a high impedancecell and poor charge storage performance. (In this micrograph 225, mostof the graphite anode 175 is physically above the micro graph shown225.) The poor adhesion between the in-situ formed Li-metallayer/interphase/Silicon interface that results in high impedance of theoverall cell also results in voids or gaps between the graphite portionof the composite anode formed in-situ.

Again, the active region interface 190 in FIG. 2B is composed ofnon-Li-salt containing adhesive (e.g. PANI) at the trench bottom 173between the anode bottom 174 and the substrate 160 prior to the currentcycling created the active region interface 190. The followingobservations are made from inspecting the micro graph image 225:

-   -   1. the silicon substrate 160 is poorly Lithiated. There is not        much Lithium (white dotted regions in the substrate 160)        distributed within the substrate 160 and it is non-uniformly        distributed—hence the conductivity for Lithium transport into        the silicon substrate is poor and consequently the respective        charge transfer resistance related to this phenomenon is high in        magnitude.    -   2. The interphase layer 230 is thick, e.g. 205 nm thick—which        illustrates a relatively high magnitude of polarization and/or        charge transfer resistance when trying to transport electrons        from the silicon material towards and/or into the PANI/Graphite        region during galvanostatic cycling and consequently, the        PANI/Li-metal/PANI/Graphite (albeit with void regions between        PANI and graphite) region upon initial current cycling.    -   3. There is a small layer 235 formed between the interphase        layer 230 and the metallic Lithium layer 240. It is believed        this layer reduces adhesion and increases internal battery        resistance. It is also believed that this layer is non-Li⁺        containing PANI or low Li⁺ concentrated containing PANI, where        the Li-conductivity is too low within the PANI material to        enable further growth of the Li-metal layer and consequently        better adhesion between the Li-metal and the silicon substrate.        Hence, the poor Lithium conductivity of the PANI material during        current cycling is observed as the cause for poor in-situ        formation of composite anode material which results in high        charge transfer resistance and poor overall cell performance.    -   4. There is a layer of metallic Lithium 240 about 33 nm thick,        but it is not flat and is uneven in thickness. The uneven        planarity of the Li-metal layer is also thought to be a        consequence of the poor-Lithium conductive PANI layer during        current cycling described above.    -   5. There is a layer of PANI 245 above the layer of metallic        Lithium 240 that is over 200 nm thick, not uniform in thickness,        not flat, and not well mixed with the anode 175 graphite—as a        large void is observed above the PANI layer and no consistently        dark or progressively darker region is observed (assumingly due        to the presence of low graphite concentration). In fact, the        region above the PANI 245 is not homogeneous and seems to have        little anode material.

When Lithium combines with silicon, there is approximately a 4:1expansion of volume of the mixture and a commensurate decrease in volumewhen the Lithium leaves. This cycling in volume of the substrate 160eventually causes stress failures in the substrate 160 which leads tofailed structural integrity, higher internal resistance, leakage,entrance of contaminants, and shorter battery lifetime. However, in thepresent invention 100, the formation of even the non-uniform Li-metallayer during current cycling suppresses the transfer of Li-metal intoand out of the silicon substrate—as no cracking, or structure breakingor mechanical breakdown is observed in FIGS. 2A and 2B. However, eventhough this structure prevents the cell-failure mechanism ofsilicon/Li-metal mechanical breakdown, the voids observed at theSi/L-metal interface and resulting high cell impedance prevent theenergy storage device from reaching its full performance potential.Hence, a remedy is required to create a seamless Silicon/Li-metal layerwhich can reversibly store Li-based charge in Silicon material withoutquick mechanical breakdown due to well known silicon electrode failuremechanism due to the roughly 4:1 volume expansion/contraction oflithiated and de-lithiated silicon material, respectfully. FIG. 2C is amicro graph image 250 showing materials, layers, and interfaces at theactive region interface 190 with a substrate 160 (over the full trenchwidth 201) with a Lithium compound mixed in with a conductive polymeradhesive and, in a novel way, placed between the anode bottom 174 andthe substrate 160 before the active region interface 190 is formed bygalvanostatic current cycling 1300. The anode 175, anode bottom 174, andsubstrate 160 are shown.

FIG. 2D is magnified 211 micro graph image 275 of part of the anoderegion interface 190 pertaining to the silicon/Li-ContainingPANI/Graphite materials interface, shown in FIG. 2C within the dashedbox region. The substrate 160, an electrically polarized trench bottom173, an electrically polarized interphase layer 230, metallic Lithiumlayer 240 and the bottom of the graphite anode component, compositedwith Li-salt containing PANI, 175 are shown.

Again, the active region interface 190 in FIG. 2D, in a novel way, hadadhesive (e.g. PANI) mixed with a Lithium compound, e.g. LiTFSi (alithium salt electrolyte), placed at the trench bottom between the anodebottom 174 and the substrate 160, prior to galvanostatic current cycling1300 which consequently enabled the creation of the active regioninterface 190 during the galvanostatic current cycling 1300. Thefollowing observations are made from inspecting the micro graph image275:

-   -   1. the silicon substrate 160 is well Lithiated. Lithium material        is diffused uniformly though out the substrate 160 in this part        of the active region interface 190 as shown by the “greyish” and        white/grey intermixed color of the substrate 160. There is        concentrated homogeneity throughout the portion of the substrate        which allows for an electrical connection between the silicon        substrate 160 and the trench-filled battery materials (e.g.,        175), up to a certain depth within the substrate below the base        of the 3D silicon trench. The concentration of Lithium gradually        decreases moving into the substrate 160A in a direction away        from the interphase 230. In preferred embodiments, regions of        the substrate 160A are saturated with Lithium ions above 0.001%        by weight of the substrate.

It is noted that in this non-limiting example, only the center 500square microns of the trench base have had the insulating layer(s)eliminated (e.g., via RIE or etching methods) so therefore this is wherethe bulk of the Lithium observed in the Silicon should and does reside.This is why FIG. 2C illustrates the majority of the lithiated silicon inor near the center of the trench-base.

-   -   2. The interphase layer 230 is thin, e.g. 21.9 nm thick, nearly        10 times thinner than the interphase layer 230 in FIG. 2B. This        reduces resistance to ionic and electron current flow and thus        enables higher theoretical performance of the overall energy        storage device. Additionally, the thinner interphase layer        enables a more consistently smooth, planarized layer as the        lithium metal layer forms on its surface during galvanostatic        cycling.    -   3. There are no extraneous layers formed—especially between the        Li-metal layer and the silicon base of trench.    -   4. There is a layer of metallic Lithium 240 about 30.5 nm thick,        that is flat and even in thickness—which illustrates excellent        adhesion between the in-situ formed Li-metal layer and the        base-of-trench/in-situ formed interphase layer 230. There is no        extraneous layer and no voids or spatial gaps between Li-metal        and Silicon based interphase layers 230.    -   5. The composite anode bottom 174 formed after galvanostatic        current cycling 1300 is homogeneous being a uniform mixture of        graphite, LiTFSI containing PANI, which is well adhered to a        Li-metal 240/Silicon-based interphase 230 bilayer. There are no        separated layers in the anode bottom 174 and the anode bottom        uniformly transitions to the graphite material above in the        in-situ formed composite anode 175.

It is believed that the uniformity, homogeneity, and good mixing ofmaterials in the bottom of the anode 175 in structure 275 causes goodadhesion, which creates a high functioning ionic and electric conductingbilayer system—that enables good containment of Lithium or high controlof Lithium mass transport, and therefore reduces structural failureswhen the volume expansion and or compression of silicon material duringlithiation/de-lithiation processes ensue. Further, it is believed thatthe increased conductivity of the uniform composite material formedin-situ (discussed more below) permitted a thinner interphase layer 230with less resistance to both electron and ion transport, which, mainlydue to the Li-containing nature of the PANI additive material before thecurrent cycling 1300, consequently permitted the formation of a welladhered, smooth, robust Li-metal layer 240 in-parallel with theformation of the Silicon-based interphase layer 230 during thegalvanostatic current cycling 1300 of the full energy storage device.The uniform thickness and excellent void-free adhesion of the metallicLithium layer 240 increases both the electrical and Li-ionicconductivity of the silicon substrate—enabling the relatively lowinterfacial charge transfer resistance and overall low impedance of thefull cell relative to the electrochemical performance of the cell shownin FIGS. 2A and 2B. Additionally, once the Li-metal layer 240 attainssufficient thickness (such as the thickness (30.5 nm) shown in FIG. 2Dobtained in the discharged state of a high performance cell) theSilicon-based interphase 230/Li-metal bilayer 240 (together referred toa bi-layer) prevents magnitudes of mass transfer of Li-ions into thebulk of the Silicon substrate 160A which would irreversibly damage ordisable the reversible-charge storing composite electrode system. It isthought that the percent by weight concentration of Lithium ions variesno more than 10 percent during the cell operation (e.g. when a currentgreater than 1 nanoampere (nA) is imposed through the composition) inthe silicon substrate, once the bi-layer (230, 240) is formed. This isconcluded based on the fact that the silicon substrate bulk 160 ishighly lithiated yet shows no sign of degradation or mechanicalbreakdown. Hence, enough Lithium material is allowed to cross into thesilicon bulk but the total concentration of the lithium material whichis integrated with the silicon bulk is minimized—resulting in nomechanical breakdown and sustainable rechargeable cell cycling. Further,it is believed that the main mechanism of charge storage in thecomposite anode results from both plating type mechanisms on theLi-metal layer 240 which is formed on top of the silicon-basedinterphase 230 as well as intercalation of Lithium ions into thegraphite anode material. Therefore, the stresses from changes in thevolume of the substrate 160 materials are reduced and structure lifetimeimproves.

As described above, the lower conductivity of the PANI only materialused in FIGS. 2A and 2B create a higher resistance to ion and electrontransport during galvanostatic cycling—as shown with the voids andspatial gaps between the silicon-based interphase layer and the Li-metallayer in FIG. 2B. Since the resistance to transfer charge across thesilicon/PANI bilayer is higher, the polarization resistance of thesilicon in contact with the PANI is higher compared with the Li-compoundcontaining PANI—resulting in a thicker Silicon-based interphase layer.

The opposite processes are observed when the Li-compound containing PANIis used prior to current cycling 1300 as shown in FIGS. 2C and 2D—whichresult in a thin, smooth, robust Li-metal layer 240 well adhered to athin (˜10× thinner than FIG. 2B) silicon-based interphase layer 230.Hence the addition of Li salt compound to the PANI additive layerenables a high functioning in-situ formed composite anode during currentcycling 1300 and a high performance resulting full energy storagedevice.

To continue, the prior art generally does not use crystalline silicon asan anode or substrate base 160, but instead uses a pulverized siliconpowder material, where conductive additives are utilized to increasecell performance (e.g. a core shell type carbon wrapped silicon-basedparticles). The novel use of crystalline silicon substrates 160 in thisconfiguration (250, 275) enables a uniquely strong interphase regionwhich is formed in-situ during electrochemical cycling, i.e. the Lithiummetal layer 240 combined with the interphase layer 230, act as awell-formed and well-adhering mechanical/chemical/electrical cap toprevent too much Lithium from cycling in and out of the silicon base160, as well as a mechanical layer which prevents cell failure due toit's ability to “cap” or mechanically and physically contain and/ormaintain the crystalline silicon structure (which expands and contractsup to 400% in volume during lithium transfer processes) which residesbelow the bilayer 160, and hence provides low resistanceelectrical/ionic connection which promotes the lifetime andelectrochemical performance of the energy storage device—thereby makingviable use of crystalline silicon as a microbattery substrate (160,160A), and in parallel, as a potential microelectronic device substrate.

Using disclosed methods and materials helps enable a solid-statebi-layer formed in-situ on a 3D patterned crystalline silicon material,which enables a high functioning full energy storage device yielding:low-interfacial impedance, a combined Li-plating and Li-ion/graphiteintercalation composite anode charge storage mechanism, andconclusively, a Li-metal/Silicon-based Interphase bi-layer (230, 240)that prevents the mechanical breakdown of Lithiated Silicon anodematerial and promotes long-lasting reversible charge storage performanceof the energy storage device.

In one embodiment, the initial galvanostatic cycles maintain arelatively low working voltage limit, e.g. 15 mV to 150 mV, at whichtime Lithium ions form Li-metal at the base of silicon trench and“plates,” e.g. saturates, the silicon substrate 160, while also beingtransported into the base silicon substrate 160 which, in parallel,forms the above described bi-layer. In parallel to this phenomenon, thesilicon-base interphase is formed directly below the Li-metal platedlayer, as electrons are polarized at the silicon side of thesilicon/Li-metal interface as they are electrochemically attempting tocombine with Lithium ions to form Lithium metal. As this polarizationprocess occurs, a polarization resistance to electron flow is observed,as electrons are “bottle-necked” at the top surface of the base of the3D silicon trench. This polarization region results in the silicon-basedinterphase 230. The degree of ease by which electrons from the siliconsubstrate 160 can combine with Li-ions in the PANI material 170, 170B,primarily determines the thickness of the observed interphaselayer—where thickness increases with the frequency or magnitude ofspatial voids between the in-situ formed Li-metal layer and thesilicon-based interphase.

Upon formation of the composite anode material containing the siliconbased interphase/Li-metal bilayer (230, 240), the lower voltage limitcan be increased upon subsequent galvanostatic reversible cycling 1300where Li-based charge is stored at the composite anode in the formof: 1) plating a thicker Li-metal layer 240 on top of the silicon-basedinterphase layer 230 and 2) intercalation type charge storage withgraphite portions of the composite anode and

3) Lithium-Silicon coordinated/alloy-based charge storage—as embodied bythe small amount of Li-charge which can irreversibly and/or reversiblytranslate into and/or into/out-of the silicon substrate residing belowthe 3D Silicon trench base.

Lithium ions are supplied from the cathode and the magnitude and/orthickness of additional Li-metal plated on the pre-plated Li-metal layer240 is dependent on the working voltage range (e.g., lower workingvoltage limit results in more/thicker plated Li-metal), and coordinatedLithium-Silicon based charge storage.

Upon reversing the polarization of the galvanostatic current cycling1300, Li-ions form from the thicker plated Lithium metal in combinationwith Li-ions being released from graphite components of the compositeanode—where these Li-ions travel through the electrolyte and areintercalated or electrochemically hosted in the cathode. The Lithiumions entering the Lithium metal layer 240 from the substrate 160, uponreverse of the initial applied current (or upon discharge of lithiumfrom the composite anode), take electrons from the top silicon region ofthe substrate 160. The interphase layer 230 forms at the base of thesilicon substrate 160 3D trench due to the polarization resistance whichresults from formation of the initial plated Li-metal layer; where theresulting interphase layer 230 is most-likely composed ofelectron-deficient and Li-ion hosting/transport-capable silicon-basedmaterial.

As a result of the current cycling 1300, this electron deficient/Li-iontransport-capable interphase layer in combination with the Lithium metallayer 240 create an bi-layer (230, 240) at the base of the 3D silicontrench which results in low-interfacial composite anode impedance, acombined Li-plating and Li-ion/graphite intercalation composite anodecharge storage mechanism, and conclusively, a Li-metal/Silicon-basedInterphase bi-layer that prevents the mechanical breakdown of LithiatedSilicon anode material through mitigating the magnitude of Lithium ionsallowed to cross the silicon-based interphase/Li-metal bilayer afterinitial cycling. Hence, after the bi-layer is formed, the majority ofthe Lithium ion exchange in the battery is occurring in the (graphite)anode 175 in combination with additional plating on and stripping fromthe Lithium metal layer 240.

Note that while the fully formed bi-layer (230, 240) largely preventsthe free conductive transport of Lithium ions from the cathode (180,185) to the silicon substrate 160, Lithium ions still migrate from thecathode (180, 185) through the electrolyte (130, 135) onto the Lithiummetal layer 240, now formed, as well as the graphite anode material 175,which is now part of the composite Silicon/Silicon-basedInterphase/Li-metal/Li-containing PANI/Graphite Anode 1475. In theLithium metal layer 240, the Lithium ions combine with electrons fromthe base substrate 160 that migrate through the interphase layer 230.Lithium ions combining with electrons form Lithium metal that adds tothe mass of the Lithium metal layer 240 when the battery 100 ischarging. The reverse process happens on discharge of the battery.

Further, the active region interface 190 (particularly the bi-layer)acts as a containment layer which is created at the trench bottom 173.This trench bottom 173 in conjunction with the insulating layers (154,156) seal the trench 150 cavity on 5 sides—where only the bottom portionof the trench 173 allows for an electrical connection between Li-ionsand electrons. Due to the base-of-trench containment layer's (bi-layer)ability to largely suppress Li-ion transport into and out of thecrystalline silicon bulk 160, volume expansion/compression in thesubstrate 160 which is induced during charge/discharge cycles,respectively, are greatly reduced, adding to the reliability,sustainable reversibility and lifetime of the battery.

Battery electrical parameter improvements are described further belowafter a discussion about the mixture, use, and transition andalternative compositions of matter including a conductive adhesive and aLithium compound.

In a preferred embodiment, a Lithium salt compound is mixed withconductive adhesive material and doping material.

The Lithium salt compound is comprised of any one or more of thefollowing: lithium hexafluorophosphate, lithium perchlorate, lithiumtrifluoromethanesulfonate, trifluoromethanesulfinimide lithium salt,Lithium bis(trifluoromethanesulfonyl)imide, lithium fluoride, lithiumiodide, lithium bromide, etc. In one preferred embodiment, the Lithiumsalt compound is LiTFSI.

The lithium salt compound comprises between 2 to 50% by mass of thecomplete lithium compound, conductive adhesive and doping materialmixture. In a preferred embodiment, the lithium salt compound comprises37% plus or minus 2% by mass.

In a preferred embodiment, the adhesive has to be conductive andadhesion promoting for silicon, graphite/carbon-based materials, andpolymer-based materials. In some embodiments, the adhesive is a polymer.In preferred embodiments, the conductive adhesive comprises any one ormore of the following: polypyrrol, polythiophene, polyaniline,polyphenylene sulfide, etc. In a preferred embodiment, the conductiveadhesive is PANI. Percentage by mass of the PANI in the conductiveadhesive mixture can range from 20% to 85% but more preferably, between30% and 60% by mass.

In preferred embodiments, the doping material is an acid comprised ofeither a Lewis acid or protic acid like camphorsulfonic acid,toluenesulfonic acid, tetraflouroboric acid,trifluoromethanesulfonimide, etc. Percentage by mass of the dopingmaterial can range from between 1% to 25% by mass but more preferably,between 5% and 15% by mass.

In preferred embodiments, the mixture is mechanically stirred orsonicated (e.g. agitated with sound energy) for many hours, overnight oras needed until homogeneity is achieved. A high vapor pressure solventmay be added in some embodiment to promote homogeneity of the mixture.For example, an acetonitrile or hexafluoro-2-propanol may be used.

The completed mixture is pipetted, cast or spin coated into/onto the 3Dsilicon substrate trenches 160, with any excess material doctor bladedoff of the substrate. The conductive adhesive mixture is then allowed toair dry and then is heated to between 60 C to 160 C for between 1 to 10minutes and allowed to cool.

As described below, the mixture created when properly used and processedwill provide the following non-limiting advantages in the energy storagedevice:

-   -   1) An electrical and Li-ion conductive medium which greatly        adheres to anode material or anode mixtures such as silicon,        carbon-based materials, graphite.    -   2) A medium which creates an electrochemically robust and low        impedance interphase layer (bi-layer) for many rechargeable        cycles, formed in-situ as the full cell is electrochemically        cycled.    -   3) A solid electrolyte material which integrates into the        composite anode material in an in-situ fashion, further lowering        the impedance of the full cell.    -   4) A charge transfer resistance lower than 100 Ohms for the full        cell. More ideally lower than 50 Ohms for the full cell. Even        more ideally lower than 20 Ohms for the full cell.

By adjusting the formulation, e.g. by adjusting the percent weight ofthe Lithium salt in the mixture, of an interfacial additive, a thinnerinterphase was achieved with superior interlayer adhesion of anelectrochemically tailored silicon/additive/anode composite.

In one preferred embodiment, the thinner interphase layer was created bydepositing a novel composition material, a mixture of a conductivepolymer adhesive (e.g. Polyaniline, PANI) and a Lithium compound (e.g.,lithium trifluoromethanesulfonate, LiTFSI). In some preferredembodiments, the device is cycled one or more times by varying currentthrough the device 1300 to form the active region interface 190 at theelectrode (e.g. anode) and silicon substrate base where the cell isformed “in-situ”.

Referring to FIG. 3, a bar graph 300 showing a comparison of chargetransfer resistance 340 and interphase thickness 360 in each of theembodiments of i. FIG. 2A and FIG. 2B (305, 310) and ii. FIG. 2C andFIG. 2D (325, 330), respectively.

FIG. 3 shows the results for cells (4 parallel microbatteries, 4 μB)with only a PANI interface additive (no Lithium based compound) used inthe 200 and 225 active region interface 190 are represented by the leftbars (305, 310) while results for cells using the novel LiTFSI-PANIcombination material in the 250 and 275 to form the active regioninterface 190 are the right bars (325, 330). The cells (made with PANIonly (200, 225) illustrated approximately a 10 times thicker interphaselayer 230, poor composite anode adhesion, PANI-based Lithiummetal/Silicon interlayer—creating voids 235 resulting in cell impedanceinduced poor performance (0.61 μAh/mm² maximum capacity, 315). The cells(250, 275) made using the novel LiTFSI-PANI material composition had a10 times thinner interphase layer 230, great composite anode adhesion(no PANI-based creation of high impedance inducing interface voids), andhigh capacity performance (1.74 μAh/mm² maximum capacity, 335).

The composite cells (four parallel microbatteries—4 μB) on one substrateelectrically connected in parallel 295, as described above and below)made with the novel Lithium compound containing PANI were compared withsimilar composite cells 295 made with a non-Lithium compound containingPANI layer as an interfacial additive. The composite cells made with thenovel Lithium compound containing PANI as an additive displayed a chargetransfer resistance 5 orders of magnitude lower 325 with 2.8 timesgreater areal discharge capacity (1.74 uAh/mm²) 325 than the othercomposite cells with no Lithium compound additive 305. The compositecells made with the PANI with a Lithium compound additive lasted 60rechargeable cycles with an average discharge working voltage range of2.5V to 1.0V, with working voltage cutoffs as low as 10 mV and high as4.7V.

Further, the composite cells made with the novel Lithium compoundcontaining PANI composition had an interphase 230 thickness 330 of about22 nm compared to an interphase 230 thickness 310 of about 205 nm forsimilar composite cells made with a PANI layer with no Lithium compoundas an interfacial additive, when current cycling 1300 the cell with thelowest cutoff voltages being 15 mV and the highest voltage being 4.7V,where sets of various working voltage limits (1.2V, 2.7V, 3.6V, 4.0V,4.2V, 4.5V, 4.7V) were utilized over 100 reversible cycles. See FIG. 5A.

Also, test modules consisting of only a single, stand-alone,approximately 2.6 mm² packaging area In-silicon microbatteries measureda full cell charge transfer interfacial impedance less than 120Ω at thepre-cycle stage with the lowest interfacial impedance observed aftermore than 80 current cycles (less than 50Ω) when made from the PANI witha Lithium compound additive.

As described in more detail below, the novel composite anode formationwas modeled by in-situ Electrochemical Impedance Spectroscopy (EIS)measurements and showed a reduction in interfacial impedance between i.graphite/LiTFSI-PANI/Lithium metal/Silicon-based interphaselayer/crystalline silicon in the anode (175, 1475) and ii. in theLithium ion conductive electrolyte plasticizer succinonitrile (SN), itsrespective capabilities to increase discharge capacity upon progressivecycling through a mechanism based on concurrently progressiveelectrochemical double charge layer (EDCL) charge storage saturation ofelectrode particles and materials, and the structural polymer component,Polycaprolatone (PCL), composition in the electrolyte (130, 135)throughout extended electrochemical cycling operations.

FIG. 4A are two Nyquist plots 400 of a single in-silicon microbatterywithin coin cell type encapsulation with one Nyquist plot taken at 0current cycles and another Nyquist plot taken at greater than 80 currentcycles.

A Nyquist plot is a graph used in Electrochemical Impedance Spectroscopy(EIS) that plots the real part of a battery impedance (associated withreal cell resistance) on the X-axis 435 and the imaginary part(associated with cell capacitance) of the battery impedance on theY-axis 430 over a range of frequencies, e.g. each point 410 (typically)on the Nyquist plot is one given frequency. The lower frequencies are onthe right side of the graph (X-axis) and higher frequencies are on theleft (of the X-axis) and the Y-axis 430 shows negative values of theimaginary part of the impedance.

The Nyquist plot in FIG. 4A shows the impedance plots for a single cell(one trench 150) microbattery within a coin cell encapsulation: i.before any current cycling occurs (top curve, 415) and therefore beforethe active region interface 190 is created and ii. after more than 80current cycles (bottom curve 420), after the active region interface 190is created. The “circle” points 410 (typically) on each curve are actualmeasured values at a given frequency and the dashed line 405 (typically)are the calculated values from a best fit RC model, e.g. 450 and 475,respectively.

FIG. 4B is the best fit RC model 450 for the data points for the “0cycle” curve 415 and FIG. 4C shows the best fit RC model 475 for thedata points on the “>80 cycle” curve 420.

The frequency measurements varied from 1 megahertz to 100 millihertz.

The graphs show that over the entire frequency range, the imaginary partof the impedance decreases after formation of the active regioninterface 190, i.e. the imaginary part of the battery impedance is loweron curve 420 than on curve 415 for every frequency measurement.

The difference in the two curves (415, 420) shows the impedance changeof the battery as the structures, layers, and chemical composition ofmaterials within the single In-silicon microbattery are changed,in-situ, as the cell is cycled due to the application of galvanostaticcycling through the battery cell for at least 80 cycles to form thefinal anode 175 and active region interface 190 as well as changes inthe electrolyte (130, 135.)

FIG. 4B is a diagram of an RC model 450 for the 0 current cycle case.The model 450 comprise a series or ohmic associated resistance, R_(s)442; in series with a parallel combination of a resistor, R1 444 andconstant phase element associated impedance 452; in series with a“Warburg impedance, W_(o1) 446; and in series with a parallelcombination of resistor, R2 448 and impedance 454 which is thought torepresent the both the interface and composition of the cathode combinedwith the bulk impedance due to the electrolyte material.

Generally, in EIS analysis, R_(s) 442 is measured/estimated as the realpart of the impedance at the higher or highest frequency data point ofthe Nyquist plot. R_(s) 442 is a pure resistive component between theelectrodes of the battery and in batteries with liquid electrolyte canbe related to the solution resistance of the electrolyte.

The parallel combination of a resistor, R1 444 and constant phaseelement (CPE) 452 is thought to be the electrical model of the activeanode region and associated interface(s) 190. R1 444 is a pure resistiveelement while impedance 452, CPE 1 (CPE, constant phase element) is acombination of both resistive and constant phase associated imaginarycomponent. The combination of R1 444 and CPE 1 (452) adds an RC timeconstant to the circuit model 450 that exists even before the activeregion interface 190 forms.

Generally, in EIS analysis of cells with high performing ion diffusion,electrode/electrolyte interface ion transport processes and/or masstransport (electrolyte migration) associated with the electrolyte (130,135), the Warburg impedance 446 measurement frequency component of thecell is observed as a near 45 degree “straight, diagonal” section of theNyquist plot, e.g. 415, 446.

The parallel combination of a resistor, R2 448 and capacitor 454 isthought to be the electrical model of the cathode interface with theelectrolyte and the electrolyte bulk. The combination adds a second RCtime constant to the circuit model 450-405, 406 and 410 relate to thisRC combination.

FIG. 4C is a diagram of an RC model 475 for the greater than 80 currentcycle case 420, i.e., after the active region interface 190 is formed.

Inspection of the model 475 reveals that the Warburg impedance 446 isgone. This contributes to the overall reduction in impedance across thebattery after formation of the active region interface 190. Theresponsible frequency range of the associated Warburg impedance modeledat 0 cycles 446 is thought to be comprised of relatively few independentfrequency data points in the high to mid frequency range only (e.g. 1250Hz to 500 Hz) as now highlighted in FIG. 5. This also indicates that thedisappearance of the Warburg impedance between 0 cycles and greater than80 cycles is due to an alteration or chemical and physical change in theanode/electrolyte interface—as the anode region associated with thecomposite anode charge transfer region are measured at frequenciesdirectly higher in magnitude than the frequencies of the Warburgimpedance (e.g. 1250 Hz to 500 Hz).

The characteristics at the interface between the cathode andelectrolyte, as well as the bulk resistive properties of theelectrolyte, also change as modeled by the change from capacitor elementC1 454 in model 450 to a constant phase element (CPE2) 469 in model 475,e.g. the element 469 now has a complex impedance associated with both animaginary (capacitance) and real (resistance) components upon extendedcycling. Such a transformation correlates with the change in both themass transfer resistance associated with ion transport in theelectrolyte as well as a change in the chemical structure associatedwith the electrolyte/cathode interface and the resulting impedance totransfer charge through or across such interface.

In addition, upon cycling more than 80 times, there was a decrease inthe value of R1 464, the resistance to transfer of charge across theactive composite anode region 175A including the transition region 172and the bi-layer region and including lithiated base silicon substrate160A.

The table below is a non-limiting summary of some of the changes thatoccur in the novel battery electro-chemistry due to the current cycling1300 to decrease charge transfer resistance of the composite anoderegion as well as the elimination of the Warburg type impedance which isobserved due to the impedance of transferring charge from anode regionprior to cycling and prior to composite anode formation. Hence, as thefull cell is cycled repetitively, the formation of the composite anode(Si/Si-based Interphase/Li-metal/LiTFSI-PANI/Graphite) 1475 increasesthe conductivity of Li-ion transport for the overall full cell.

Region 490 of the Nyquist plot 400 is magnified and shown in more detailin FIG. 5.

FIG. 5 is a magnified region 490 of the Nyquist plot shown in FIG. 4Aand will be used to determine the values of R1 444 before and after theformation of the active area interface 190. The experimental data pointsare the hollow circle points in the plot where the dashed line is thetheoretical model fits (450, 475) of the experimental data points. Itshould be noted that from the Nyquist plots shown in FIG. 5, one canobserve a partial semicircle due to the R1/CPE1 parallel combination ofthe cell at 0 cycles associated with the pre-cycled composite anoderegion. Upon more than 80 reversible cycles, the Nyquist plot associatedwith the cell changes significantly, where a much smaller portion of theassociated semicircle is observable.

Upon more than 80 reversible cycles, the semicircle approximation of theR1 (464)/CPE1 (468) visually yield an elongated-type semicircle—due tothe in-situ formation of the composite anode material. Through thehigh-to-mid frequency semicircle approximation illustrated for 420 bythe fitted model of best fit, it is apparent that higher frequencyregions become active (not shown experimentally since both 410 and 420were measured with the same frequency range 1 MHz to 100 mHz) due to thein-situ composite anode formation. More specifically, it is believedthat the formation of the Si-based Interphase 230 and Li-metal 240bilayer is responsible for the additional higher frequency associatedchanges in the magnified region of the Nyquist plot 420 and theresulting elongated constant phase element which represents the R1(464)/CPE1 (468) modeled semicircle. The point of origin of theapproximated semicircle (leftmost X-intercept) is approximately the sameas the pre-cycled Nyquist plot 410, thereby further validating thesemicircle approximation as the resulting Rs (Ohmic/Series resistance)of the >80 cycle Nyquist plot 420 is approximately the same (˜15Ω) asthe pre-cycled Nyquist plot 410. The relative dimensions, location andmagnitude of the said post-80 cycles semicircle is affirmed by the valueof R1@>80 cycles as calculated by the RC circuit model of FIG. 4C, wherethe diameter of the semicircle is aligned with the X-axis 435 and thelength of the diameter gives the value of R1 444.

As shown, the value of R1 444 in model 450 is 87Ω at zero current cyclesand before formation of the active region interface 190. The value of R1464 in model 475 is 38Ω above 80 current cycles and after in-situformation of the active composite anode region interface 190. Theresistance R1 has decreased 56% as a result of the formation of thenovel in-situ composite anode active region interface 190 which enableshigher conductivity of Lithium ions and lower resistance to transfercharge across the composite anode region.

The table below lists some of the non-limiting improvements to theelectro-chemistry and performance of the novel battery 100 with a novelactive region interface 190.

Some Impacts on Charge Transfer Resistance from Composite AnodeFormation

Key 0→80 Current Cycles Impact R1: Anode Ω 56% decrease Formation of LowΩ Si/Si-based Interphase/ Lithiated Si/PANI/Graphite Composite Anode 172Wol: Mass Decrease from Mass Transfer Resistance Transfer Ω 2.7 Ω to 0 Ωassociated with Anode to Polymer Electrolyte Ω Eliminated Upon CompositeAnode Formation.

FIG. 5A shows one stand-alone energy storage device test module showingdischarge capacity with the data points in the bottom of the plot wherethe left side Y-axis illustrates discharge capacity for each cycle (inμAh/mm²) and discharge voltage onset with the data points on the top ofthe graph where the right side Y-axis illustrates discharge voltageonset (in volts) vs number of current cycles. Note that dischargevoltage onset refers to the starting voltage immediately aftergalvanostatically discharging the cell (within the first second ofapplying cell discharge inducing current). This data was taken using onemicrobattery, i.e. one trench 150, on one substrate 160 encapsulated ina coin cell encapsulation (192, 194.)

The single microbattery yielded a top areal capacity greater than 1.50uAh/mm² after operation, with more than 100 operational rechargeablecycles obtained with an average working voltage range of 3.5V to 1.0V(500); yet cycling the cell with the lowest cutoff voltages being 15 mVand the highest voltage being 4.7V, where sets of various workingvoltage upper limits were utilized throughout the more than 100 cyclesof the cell: 1.2V 510, 2.7V 520, 3.6V 530, 4.0V 540, 4.2V 550, 4.5V 560,4.7V 570. Minimum rechargeable capacities of these test modules (1microbattery on a substrate 160) were double that of other (4microbatteries 295 on a single substrate 160 electrically connected inparallel) and enabled an 18 times reduction in packaging area withnearly a 3 times reduction in composite cell impedance and consequently,a 1.2 volt increase of onset discharge voltage.

FIG. 5A illustrates the effect upon the rechargeable performance of thecell when applying the pre-cycling treatment. The initial cycling of thesingle microbattery cell yielded a low discharge onset voltage 510 andcorrespondingly, very low discharge capacity (bottom of plot data pointsdirectly below 510 data points). This cycle schedule only charged thecell to 1.2V prior to discharge. In fact, the impedance of the cell wastypically too great at this stage in its lifetime to charge the cell toa higher voltage. The discharge voltage onset was in generalapproximately 1.0V, yet due to the relatively low discharge voltageonset virtually no capacity was yielded. At this point in the cell'slifetime, the composite anode material as well as the stablesilicon-based interphase/lithium metal bilayer were in the preliminarystages of being created.

The next cycle utilizes an upper working voltage cell limit of 2.7V,where the time to charge the cell to this voltage was much higher thanthe previous cycles 510, as the resistance of the cell is decreasingwhen the cell upper voltage limit is progressively, incrementallyincreased. In this cycle, we observe a jump in discharge voltage onsetto approximately 2.5V 520 and correspondingly, yields a dischargecapacity of approximately 0.12 uAh/mm². The increase in magnitude of theupper working voltage limit, in this case, enabled the initial formationof the working composite anode containing the silicon-basedinterphase/Li-metal bilayer (230, 240.) Hence, because the compositeanode and silicon interface have been formed, where the electrochemicalpre-cycling treatments (510, 520) promote the intimate adhesion betweencomposite layers which lowers the total impedance the cell experienceswhen galvanostatic current cycling 1300, the cell experiences arelatively significant increase in the ability to retain charge(maintain State of Charge (SOC)). Now, since the highly adheredcomposite layers are formed, current does not leak out of the activeregion of the cell with the direct result being a proportional loweringin voltage (leaking of charge) when trying to discharge themicrobattery. At this point, the impedance of the cell is low enough tocharge the cell to this voltage in a relatively low amount of time, andhence higher voltages can be employed.

The next cycle increases the working voltage upper limit even further to3.6V, where even higher performance is observed in both the dischargeonset voltage (˜3.1V) as well as the discharge capacity (˜0.20 uAh/mm²).Hence, it is believed that the composite anode and essentialsilicon-based interphase/lithium metal bilayer is now even lower in itscontributions to overall cell impedance.

The remaining (>90) cycles also had their upper working voltage limitprogressively increased in independent cycle sets with magnitudes of:4.0V 540, 4.2V 550, 4.5V 560, 4.7V 570, with all discharge voltage onsetmagnitudes revealing approximately 3.75V, 3.85V, 4.1V, 4.2V magnitudes,respectively, during their independent cycle set. At this point, thesingle microbattery has developed a sustainably functioning, lowimpedance composite anode containing a silicon-based interphase/lithiummetal bilayer which enables very low charge transfer resistance (FIG. 5)of the energy storage device. Hence, once the composite anode containinga silicon-based interphase/lithium metal bilayer is fully formed afterthe first 3 pre-cycle stages, the entire cell can function like a highperformance microbattery maintaining high SOC upon charging (lowleakage=little to no drop in discharge voltage onset potential magnitudefrom cycle to cycle).

In summary, FIG. 5A illustrates the cycling performance results whichare impacted by and during the formation of the composite anodecontaining the Si-based interphase/Lithium bilayer 230, 240.) Theprogressive increase in the cell's ability to charge to higher uppervoltage limits as well as the cell's ability to hold and maintain thestate of charge (SOC) are direct results of composite anode and keybilayer formation. The first 3 pre-cycling stages (510, 520 and 530)condition the cell to enable in-situ composite cell and bilayerformation. Where the remaining cycle sets for >90 cycles (540, 550, 560and 570) easily maintain a high voltage upon charge (all sets showeddischarge voltage onsets>3.9V) which then enables high dischargecapacity performance (as high as 1.50 uAh/mm²). Hence, FIG. 5illustrates the magnitude of charge transfer resistance which isdecreased upon formation of the composite anode containing silicon-basedinterphase/lithium metal bilayer, whereas FIG. 5A displays theperformance impact of the in-situ composite material formation and theelectrochemical method of pre-cycling the cell to enable in-situcomposite material formation via independently customized stages orcycling sets.

FIG. 6 is a micro graph image of a cross section 600 of a solid polymerelectrolyte (SPE) with a component ratio of 10:1 Polycaprolactone (PCl)to Succinonitrile (SN) where the polyacrylnitrile (PAN) component isobservable in FIG. 6A, the top region 605 of the micro graph as afabric-like inter-woven layers of PAN material which is saturated withthe PCl/SN mixture. Also shown is an inserted image 605 which is atop-down SEM micro graph of the same sample where the homogeneity of thePAN matrix saturated with the PCl/SN mixture is illustrated.

In a preferred embodiment, the electrolyte 138 is solid under operationconditions and comprises a top layer of 130T of a Lithium ion conductivematerial, a bottom layer of Lithium ion conductive material 130B,separated by a separation layer 135. The Lithium ion conductivematerials allow Lithium ions to move between the cathode (180, 185) andanode 175 and ultimately to external connections (192, 194) of theenergy storage device/battery 100. In some preferred embodiments, thetop 130T and bottom 130B Lithium conductive layers 130 are made from aLithium salt compound 130 immersed in a Lithium Conductiveplasticizer-type Medium Succinonitrile (SN) and a polymer typestructural material polycaprolactone (PCl). In some preferredembodiments, the Lithium salt compound 130 is LiTFSi.

The separation layer 135 performs the function of a dielectric materialwhere the separator maintains electrical separation between the cathodeand anode electrodes, thereby preventing short circuiting of the cell orresistance to ion/electron separation processes. In a preferredembodiment, the separation layer 135 is polyacrylnitrile (PAN.) The PANis a compressible material which allows the electrolyte (e.g. SPE) toexpand and contract as the Lithium metal layer 240 grows and shrinks inthickness during charge and discharge cycles, respectively. PAN'scompressibility property also helps in varying the thickness of the SPE.The mechanical flexibility of the PAN material aids in the integrationof separator material into the 3D patterned silicon trenchfeatures—where PAN's mechanical flexibility can maintain good adhesionof anode/electrolyte/cathode materials both inside and above the planeof the silicon trench.

In preferred embodiments, the Lithium ion conductive layers 130 startout as a mixture of a first material that has good Lithium ionconductivity and second material that has good structural as well asLithium ion conductivity properties. During the galvanostatic cycling,the first and second materials combine uniformly, where plasticizer-likeLithium-conductive components (e.g., succinonitrile (SN)) representingone of the lithium ion conductive layer mixture materials has beenillustrated in the past to progressively solvate around mixture andcomposite materials and the Lithium ion conductivity of the resultingelectrolyte and/or electrolyte/electrode interface(s) composition(s)goes up, concurrently with the decrease of ion transport resistanceacross these regions of the cell. Part of this increased conductivitywas shown by the Warburg impedance W_(o1) 446 going to zero afterformation of the active region interface 190—as described above (FIG. 5)with the establishment of the elongated R1 (464)/CPE1 (468) parallelmodel element which arises from the creation of the Si-basedInterphase/Li-metal bilayer.

It is also desired that while the active composite anode regioninterface 190 is formed, the electrolyte 138 (e.g. SPE when comprisingsolid materials) be in 3D conformation with the surfaces that contain itand that the SPE adheres well to the anode 175 and cathode (180, 185)structures. These properties further enable the in-situ processing andcreation of the high performing electro-chemistry of the energy storagedevice.

In a preferred embodiment, the material having a good Lithium ionconductivity is Succinonitrile (SN) in combination with the LiTFSILithium salt. Other materials with high Lithium ion conductivities whichcan maintain conformal SPE and/or polymer type electrolyte propertiesmay also be used. For example, various combinations of the followingmaterials would be comparable in desired properties: polymer structurehost material can comprise any one or more of the following:poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO),Poly(dimethylsiloxane), Poly(vinyl chloride), etc. The Lithium compoundcomprises any one or more of the following: lithium hexafluorophosphate,lithium perchlorate, trifluoromethanesulfonimide lithium salt, lithiumchloride, Lithium Bromide, LBF₄, etc., and where the plasticizingmaterial can be poly(ethylene glycol) (PEG), aprotic organic solvents,dimethylsulfoxide (DMSO), etc. However, it should be noted that the useof succinonitrile is the primary plasticizer-like component in currentstate of the art work which has been shown to increase capacitymagnitudes upon progressive cycling.

In a preferred embodiment, the material having a good structural andconformational properties is Polycaprolactone (PCl.) Other material withsuitable polymer structure host material. may also be used. For example,polymer structure host material can comprise any one or more of thefollowing: poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO),Poly(dimethylsiloxane), Poly(vinyl chloride), etc.

Testing showed (see discussion of FIG. 7) that by varying the ratio ofPCl to SN, both the SPE thickness and the conductivity (e.g. to Lithiumions) can be changed. For example, adding more PCl increases thethickness, adhesion, and structural integrity of the electrolyte butdecreases the conductivity. (A 10:1 ratio of PCI to SN was chosen forthe micro graph image 600 because this ratio clearly showed both theconductive 130B and PAN 135 layers). Typically, adding more plasticizermaterial to a polymer electrolyte mixture will significantly increaseconductivity of electrolytes at ambient temperatures, but will come atthe cost of deteriorating the polymer structure host mechanicalintegrity.

Where the PCl/SN combined with LiTFSI salt and electrospun PANseparator—it was found that the composite SPE formed in the PCl/SNratios used led to a trend which displayed increasing ionic conductivitywith increasing SN mixture component, yet also increasing thickness ofthe SPE composite as the PCl/SN ratio became larger (e.g., 10:1 to 2:1).Such phenomena is thought to be due to the ability of the SN plasticizerto breakdown or more completely saturate the PCl component when theconcentration of the plasticizer used is relatively high. The effectthis has on the composite SPE matrix is to unsaturate the PCl materialwithin/on the PAN matrix—thereby decreasing the compressibility of theSPE composite and creating an overall thicker SPE composite electrolyte(e.g., by decreasing the relative PCl component which acts as the “glue”to hold the interwoven PAN layers together, the PAN layers can moreeasily separate from one another and expand spatially—thereby increasingthe overall SPE thickness).

The level of conformal adhering, Lithium ion conductivity, and SPEthickness are all “tunable” by adjusting the ratio of the structuralmaterial to the conductive material, e.g. PCl to SN in the SPE compositeelectrolyte.

Factors that increase Lithium ion conductivity include: reducingpolarization resistance of the electrolyte material, The SPE thickness.

Generally, it is known that decreasing the thickness of electrolytematerials can increase the rate or power capabilities of the energystorage device (e.g. decreases the resistance to ion transport throughthe electrolyte). However, increasing or decreasing the thickness of theelectrolyte/separator layer in composite electrolytes such as SPE's canhave a multi-faceted effect. For example, in the case of the presenttrend, the electrolyte component (PCl) was decreased, but led to aconsequential increase in SPE thickness due to PAN “fluffing out” andincreasing the SPE thickness—yet the added relative ratio of SN in thecomposite is known to increase ion conductivity of the resulting SPEcomposite which is observed as the formulation is changed from 10:1 to2:1 (observed in FIG. 11).

Decreasing the relative surface area related to ion-based chargetransfer processes.

High Lithium ion conductivity decreases the resistance for ion transportthrough the electrolyte. As resistance to transport the ions through theelectrolyte decreases, the relative overpotential (how much potential(voltage) is lost during the initial charging or discharging of thecell) also decreases. This lowering of resistance and consequentialoverpotential is directly measured with the polarization resistance (Rp)of the electrolyte material—as observed with the semicircles, and fittedRC models thereof, resulting from Nyquist plots of symmetric Electrolytecells tested via electrochemical impedance spectroscopy (EIS).

Polarization resistance is the transition resistance between electrodes(e.g. anode and cathode) and the electrolyte, e.g. SPE 138. Morespecifically, polarization resistance is the resistance to polarizecharge within a charge-conductive medium to a magnitude which enablescharge-transfer from the charge-conductive medium to another adheredmedium. An increased resistance to the flow of ionic current in theelectrolyte material bulk and the SPE's respective interfaces reducesthe voltage across the battery through increasing the overpotentialrequired for ion transport processes (energy barrier to “start” ionmovement is high in high polarization resistance type cells) and reducesoverall battery performance.

Ionic conductivity (IC) is defined as equal to

$= {\frac{1}{R_{P}}\left( \frac{e}{S} \right)}$where:

e=thickness of the SPE. In this structure 600, the total SPE thicknesswas 3.8e-3 cm.

S=Surface area, in this structure 600 the Surface area=1.98 cm²

Resulting in an IC of 4.25e-4 S/cm (Siemens per centimeter.)

FIG. 7A is a drawing of a symmetric cell test device 700 for measuringcurrent flow thorough an impedance of one or more solid polymerelectrolytes (SPE) units with different novel ratios of electrolytecomponents Polycaprolactone (PCl) and Succinonitrile (SN) separated bypolyacrylnitrile (PAN.)

A test device 700 like this was used to obtain the data in FIGS. 8through 11.

An electric potential (e.g., 50 mV) with a frequency that can be variedis applied though 2 electrical connections 705 each of which isconnected to a conductive (preferably copper) disc 720. The surfaceareas 710 of the discs are chemically cleaned (e.g., with Nitric acidsolution) prior to use to provide a good electrical connection to aSolid Polymer Electrolyte (SPE) 725. The SPE 725 is made of a separationlayer 135, preferably PAN, separating an electrolyte layer 130 on eitherside of the separation layer 135. Each electrolyte layer 130 iselectrically connected to the clean surface 710 of an oppositeconductive disc 720 to form an electrical circuit through the SPE. Testsare run where a voltage is applied across the 2 electrical connections705 and the frequency of the voltage is swept from a high to lowfrequency. Impedance magnitude and the respective phase angle with theapplied voltage are measured and recorded, independently, at a pluralityof frequencies.

FIG. 7B is a resistive/capacitive (RC) electrical model of differentexample solid polymer electrolytes (SPE) tested using the device in FIG.7A.

The model 750 comprises a resistance, R_(s) 762; in series with aparallel combination of a resistor, Rp 764 and capacitive impedance C1768; in series with a “Warburg impedance, W_(o1) 766.

Generally, in EIS analysis, Rs 762 is measured/estimated as the realpart of the impedance at the higher or highest frequency data point ofthe Nyquist plot. See FIGS. 8 through 10. Rs 762 is a pure resistivecomponent between the conductive discs 720 of the test device 700. Rs isoften associated or attributed to contact resistance relating to thetesting of a cell or device.

The parallel combination of a resistor, Rp 764, and capacitiveimpedance, C1 768, add an RC time constant to the circuit model 750.

A Warburg impedance 766 is connected in series.

As discussed in FIG. 4A, the actual data measured is placed on Nyquistplots (see FIGS. 8 through 10) where a dot/circle at each givenfrequency applied is the experimental data. The RC circuit model 750 isused to best fit a curve to the actual data. The best fit curve isrepresented by a dashed line of the Nyquist plots presented in FIGS. 8through 10. Nyquist plots are done for three different ratios of PCl toSN in the electrolyte layers 138.

FIG. 8 is a Nyquist plot 800 of a solid polymer electrolyte (SPE) with apolyacrylnitrile (PAN) separator and a 10:1 ratio of PCl to SN in theelectrolyte layers 130. Using techniques described in FIG. 4, fittingthe RC model from FIG. 7B determines an Rp equal to 81.4Ω.

FIG. 9 is a Nyquist plot of a solid polymer electrolyte (SPE) with apolyacrylnitrile (PAN) separator and 3:1 ratio of PCl to SN in theelectrolyte layers 130. Using techniques described in FIG. 4, fittingthe RC model from FIG. 7B determines a Rp equal to 4.4Ω.

FIG. 10 is a Nyquist plot of a solid polymer electrolyte (SPE) with apolyacrylnitrile (PAN) separator and 2:1 ratio of PCl to SN in theelectrolyte layers 130. Using techniques described in FIG. 4, fittingthe RC model from FIG. 7B determines a Rp equal to 1.3Ω.

FIG. 11 is a thickness and conductivity of a solid polymer electrolyte(SPE) measured as a function of polycaprolactone (PCl) to Succinonitrile(SN) ratios in the polymer formulation of the electrolyte.

Using known EIS techniques, some described above in FIG. 4A, thecomponents of the circuit model 750, e.g. Rs 762 and Rp 764, aredetermined and the Lithium ionic conductivities (in mS/cm) of the SPE725 are determined and plotted 1100 at each of the three PCl/SN ratios:10:1, 3:1, and 2:1.

The data shows the multi-faceted interplay of the polymer structurehost, plasticizer with respect to relative concentrations and how theyimpact SPE structure, thickness, ionic conductivity and morphology. Allcritical parameters which influence a given application and/or 3Dsubstrate.

A thicker, less compact SPE can result in higher ion conductivity(higher relative SN concentration) but less structural integrity (lowerrelative PCl concentration) and therefore more difficulty of 3D & 2Dintegration due to non-compactness

A thinner, more compact SPE can result in a low Ion conductivity (lowerrelative SN concentration) but high structural integrity (higherrelative PCl concentration). However, difficult 3D integration arise dueto decreased flexibility.

A thickness/compactness ratio of about 3:1 for the SPE is just right forboth 3D and 2D integration and has relatively high (0.425 mS/cm) ionicconductivity in ambient conditions. SPE electrolytes for any givenapplication should standardly have ˜10E-4 S/m ion conductivity whenusing plasticizer components.

Using a 3:1 ratio afforded advantages in 3D and 2D integrationcapabilities. This formulation enables high connectivity/adhesionbetween cell components inside (composite anode) and outside of trench(cathode) in one preferred structure 100 in FIG. 1.

FIG. 11A is a micro graph image of a cross section of two layers of asolid polymer electrolyte (SPE) with a 10:1 ratio of Polycaprolactone(PCl) to Succinonitrile (SN) components saturating electrospunpolyacrylnitrile (PAN) showing an SPE thickness of 27.8 μm and yieldingan ionic conductivity of 0.0172 mS/cm.

FIG. 11B is a micro graph image of a cross section of two layers of asolid polymer electrolyte (SPE) with a 3:1 ratio of Polycaprolactone(PCl) to Succinonitrile (SN) components saturating electrospunpolyacrylnitrile (PAN) showing an SPE thickness of 37.6 μm and yieldingan ionic conductivity of 0.425 mS/cm.

FIG. 11C is a micro graph image of a cross section of two layers of asolid polymer electrolyte (SPE) with a 2:1 ratio of Polycaprolactone(PCl) to Succinonitrile (SN) components saturating electrospunpolyacrylnitrile (PAN) showing an SPE thickness of 84.57 μm and yieldingan ionic conductivity of 3.286 mS/cm.

FIG. 12 is a flow chart showing an method of making 1200 an energystorage device 100 having a solid polymer electrolyte (SPE) (for example130B, 135, 130T or 725), an anode 175 in a full 3D trench 150 in asilicon substrate 160, and a partially formed novel active regioninterface 190 between the anode 175 bottom 170B and the substrate 160.The process 1300, below, fully forms the active region interface 190.

In a preferred embodiment, the substrate 160 is silicon, crystallinesilicon, and/or doped silicon, as described above. A partially formedactive region interface 190 is initially made by mixing a conductivepolymer adhesive like PANI with a Lithium compound, e.g. a Lithium saltlike LiTFSI. Alternative embodiments use PANI without mixing a Lithiumcompound. In a preferred embodiment, the anode 175 is graphite.

In a preferred embodiment, the SPE 138 has a bottom layer 130B and a toplayer 130T with a separation layer 135. The bottom 130B and top 130Tlayer of the SPE are initial formed with a ratio combination of astructural component like Polycaprolactone (PCl) and an ionicallyconductive plasticizing component like Succinonitrile (SN). In apreferred embodiment, the separation layer 135 is made ofpolyacrylnitrile (PAN).

In a preferred embodiment, the cathode (180, 185) is made from aconductive metal sheet, e.g. aluminum or an aluminum alloy, attached toa Lithium containing material layer 180 like Lithium Iron Phosphate(LFP).

In step 1210, 3D trench features are fabricated, e.g. the trenchcavities 150 are etched into base substrates 160 like silicon. One ormore insulating layers (154, 154T, 156, 156T) are formed. Any insulatingmaterial is removed, e.g. by an etching process from the active area 120at the bottom of the trench 150.

In step 1220, the conductive polymer adhesive, e.g. PANI, is mixed withLithium compound, e.g. LiTFSI. (In alternative embodiments, unmixedconductive polymer adhesive, e.g. PANI is used.) This material isdeposited on the active area 120 on the trench bottom 170B. Optionally,this material is deposited on the trench walls. The material isdeposited by casting methods, pipette methods, spin coating, doctorblading, or any single or combined method which conformally deposits theconductive polymer adhesive on the base of the 3D silicon trenches.

After depositing, the PANI or PANI mixture is heated from 1 to 10 min atbetween 60 C to 160 C to cross link the polymer material together.

In step 1230, the anode 175 material, in a preferred embodimentgraphite, is deposited in the trench 150 via slurry casting, pipettemethods, spin coating, spin coating, etc. Any excess graphite materialis removed from the field surface through doctor blading techniques (toscrape excess material away from surface via a metal or glass blade). Inone embodiment, the anode is added to the trench, followed by polymerelectrolyte material, followed by more anode material. In anotherembodiment, polymer electrolyte material is added to the trench prior toany anode material—where the anode material is added on top of thepolymer material deposited in the trench. In yet another embodiment, thepolymer electrolyte material is pre-mixed with the anode material(adding between 1% to 60% by mass or volume polymer material to anodeslurry material), then deposited in the trench. Then the anode is airdried in air followed by vacuum drying between 2 to 48 hrs. Afterdrying, the anode 175, is optionally, briefly pressed with conformaltrench fitting molds using hand applied pressure. Another option is toallow the anode material or composite anode/polymer electrolyte materialto briefly dry (30 min to 6 hrs) in air or 20 min to 2 hrs in a vacuumoven, and then briefly press with conformal trench fitting molds usinghand applied pressure. All these processes 1230 while the anode 175materials or anode/polymer composite materials are residing in thetrench 150.

In step 1240, the SPE (130B, 135, 130T) is deposited on the top of theanode 175 and the top either of the substrate 160 or any insulatinglayers (154T, 156T.) The electrolyte layer 130B, the separation layer135, and the top electrolyte layer 130T are sequential deposited by anyof the following methods: casting, pipette methods, spin coating, etc.for the polymer electrolyte and direct layer application with the PANseparator material (e.g., dicing out suitable PAN dimensions andlayering it on top of polymer electrolyte which resides on the anode oranode/polymer electrolyte composite). Additionally, thePolymer/PAN/Polymer SPE can be fabricated in mass (sheets) and thendiced when the SPE material has condensed. Then the diced SPE can beinserted into the 3D trench or on top of it. Heat treatments can also beapplied to better adhere the SPE to surrounding layers, as thetemperature of the SPE will determine the relative viscosity and wettingor adhesion capability of the polymer component of the SPE.Additionally, the PAN material can be adhered/laminated to the cathodematerial in a preliminary fashion. Then the polymer electrolyte can beapplied in the trench/on the surface of the anode and then thePAN-coated cathode material can be applied to the polymer electrolytewhen inserted in the trench and/or on the polymer electrolyte material.The utilization of pressure and/or applied heat (35 C to 65 C) thepolymer electrolyte material will soak through the PAN material adheredto the cathode, thereby forming the polymer/PAN/polymer SPE 138 and inthe process will make intimate contact with both the anode and cathode(see below). The electrolyte bottom 134 is in physical, chemical, andelectrical contact with the anode 175 as facilitated with temperatureand pressure control of the cell stack—as the viscosity and wettingcapability of the polymer electrolyte material is controllable uponapplication of heat (e.g., 35 C to 65 C) and maintaining pressure duringthis process and while the completely adhered cell cools enablesphysical, chemical and electrical contact of the final formed SPE withother active battery materials.

In step 1250, the cathode (180, 185) is made and connected. The cathodeLithium compound layer 180 is disposed on a cathode conductive layer185, e.g. aluminum or aluminum foil or aluminum composite (e.g.,aluminum—tantalum composite material). In a preferred embodiment, theLithium compound layer 180 is made of Lithium Iron Phosphate (LFP) orNickel Manganese Cobalt (NMC) or Lithium Manganese Oxyfluoride (LMOF).The Lithium compound layer 180 and the cathode conductive layer 185adhere and are electrically and structurally connected. The bottom 181of the Lithium compound layer 180 is attached to the top 136 of the SPEto make a good structural and electrical contact.

In step 1260, the substrate 160, anode 175, electrolyte (130B, 135,130T), cathode (180, 185) and all other internal components and layersare optionally encapsulated 1260. In one preferred embodiment, an upper192 and lower 194 coin cell casting are pressed and crimp sealed (198,and 199, respectively) together. In alternative embodiments, the batterycell structure may be encapsulated or not with coin cell castings (192,194) and/or be sealed by known semiconductor methods on a substrate 160and/or connected to other components on that substrate 160. In latterstages of the manufacture, circuits containing one or more of theseenergy storage devices 100 could be diced from a wafer have a pluralityof these circuits.

FIG. 13 is a flow chart showing a method of galvanostatic currentcycling 1300 of an energy storage device 100 to fully form the novelactive region interface 190 and the inter-dispersion/working form of thesolid polymer electrolyte (SPE) prior to normal cycling.

Once the energy storage device 100 is made with initial (e.g. precursor)materials, in preferred embodiments a current source is connected acrossthe terminals (e.g. 192, 194) of the device 100 in order to cyclecurrent of different magnitudes through the device 100 at desiredworking voltage range(s). As explained in this disclosure, this currentcycling 1300 causes electrochemical changes in parts of the device 100to improve performance of the device 100 over the entire lifetime ofoperation.

The Galvanostatic Cycling, Pre-Cycle Stage 1 is step 1310 of the currentcycling process 1300. Step 1310 first charges the cell 100 by applying acurrent between 1 uA to 150 uA. This charge cycle ends when the terminalvoltage of the device reaches an upper voltage limit of between 500 mVand 2.5V. The cell 100 is then discharged by applying a current in theopposite direction at between 1 uA and 25 uA. This discharge stops at alower voltage between 0.010V to 0.050V. At this point Pre-Cycle Stage 1either terminates or can be repeated up to 20 times and then terminated.

During Pre-Cycle Stage 1, e.g. cycling at low current magnitude at lowupper voltage, the base substrate is being saturated with Lithium ionsthat are moving from the cathode 180 through the SPE and anode 175because there the Lithium metal 240 and interphase 230 layers are onlybeginning to form.

As the Lithium metal layer 240 forms, Lithium ions from the cathode 180are progressively suppressed from entering or leaving the substrate 160and the interphase layer is forming where electrons are moving out ofthe top of the silicon substrate to combine with Lithium ions from thecathode 180 to make more Lithium metal in the Lithium metal layer 240during device 100 charge cycles. The opposite happens upon reversing thepolarization of the applied current. However, there is relatively lessLithium ion migration into or out of the silicon substrate 160 once theLithium metal layer 240 is formed. This greatly reduces stresses,cracking, and dendrite formation in the substrate 160 because volumechanges in the substrate 160 due to changing Lithium ion concentrationare reduced and a robust top Lithium-containing layer well adhered tothe silicon substrate prevents silicon material degradation andtherefore maintains a low ion and electron resistance.

Use of the precursor materials, the conductive polymer adhesive mixedwith Lithium compound, more preferably a Lithium salt, and even morepreferably LiTFSI, increases the conductivity/mobility of Lithium ionsthrough the PANI in the forming active composite anode region interface190 so the Lithium metal and hence the Lithium layer 240 initially canform when Li-ions from the cathode connect with electrons from the basesubstrate 160. Moving in an opposite direction upon application ofopposite polarized current, the electrons from the substrate 160 movetowards the cathode via an external circuit, the Lithium ions from thecomposite anode initially move into the SPE as Lithium is transportedfrom anode material (e.g., via de-intercalation from graphite and/orstripping from Li-plated metal) and into the cathode host material.

As the Lithium metal layer 240 forms, the bulk of the lithium which iscontained in the silicon substrate 160 is prevented from returning intothe electrolyte/cathode and progressively, Lithium from the electrolyteregion is prevented from crossing the Li-metal layer and reacting withsilicon substrate material 160 (the Lithium ions from the cathode 180are prevented from entering the substrate 160). These electrons andLithium ions combine in the Lithium metal layer 240 and cause it to growwhile charging. The Lithium metal layer 240 also prevents (essentially)the Lithium ions saturating the substrate 160 from leaving the substrate160—thereby preventing the well known Silicon-Lithium degradationmechanism due to the up to 400% volume change during silicon lithiationand de-lithiation processes.

As electrons leave the surface of the substrate in the active area 120,the interphase layer 230 forms in the region where electrons have beenpolarized in the substrate 160 near the silicon/conductive adhesiveinterface. Since the Lithium ion conductivity is high, initially, due tothe conductive polymer adhesive mixed with the Lithium salt compound,the Lithium metal layer 240 and interphase 230 layers forms in anenergetically favorable fashion and the interphase layer which enablesthe Lithium plating mechanism is much thinner than in the prior art. Thelayers are also smoother, do not contain voids or gaps or any additionalmaterial between the Silicon/Lithium plated layer and provide betterstructural adhesion and electrical and chemical connection compared withmore resistive materials which create relatively thicker interphaselayers, that enable a less homogeneous plating mechanism—creating voidsand gaps between the interphase and lithium metal layers—resulting inhigher impedance and therefore poorer performing energy storage devices.

The “bi-layer” of Lithium metal 240 and interphase layer 230 alsoprovide better containment for Lithium ions, either saturated in thesubstrate 160 or contained in the trench 150. Additionally, andcritically important, the “bi-layer” enables very low impedance at theSilicon/Li-metal/PANI/Graphite interface when moving charge (e.g., ionsand electrons) across the respective interface—which enables highperformance of the energy storage device.

Once the active region interface 190 is formed there is little Lithiumion migration in or out of the substrate 160 reducing substrate anddevice cracking from large volume changes of the substrate 160.

The formation of a well formed/adhered “Bi-layer” of Li metal andsilicon based interphase allows electrons to meet Li⁺ and plates on Limetal layer so as the Lithium metal layer 240 grows the Li-metalassociated anode bottom 170B is expanded into the anode 175 uponcharging and compresses upon discharge, where at full discharge aminimum Li-metal layer remains well adhered in the bi-layer fashion.Hence the bi-layer is the key to sustainable, rechargeable Li-ion cellhigh performance.

Step 1320, the Galvanostatic Cycling, Pre-Cycle Stage 2, begins whenPre-Cycle Stage 1 terminates. Start by charging the cell 100 by applyinga current between 1 uA to 115 uA. Stop applying the charge current whenthe upper voltage is between 500 mV and 3.5V, a higher voltage rangethan in Pre-Cycle Stage 1. Discharge the cell 100 by applying a currentin the opposite direction at a magnitude between 1 uA and 25 uA, withthe applied discharge current being the same or higher magnitude thanthe discharge current applied in Pre-Cycle Stage 1 1310. Stopdischarging the cell when the lower voltage is between 0.010V to0.0.500V, with the lower voltage cutoff magnitude being the same orhigher magnitude than the lower voltage cutoff magnitude utilized inPre-Cycle Stage 1 1310. Stop Pre-Cycle Stage 2 or repeat Pre-Cycle Stage2 Charge/Discharge schedule up to 20×.

Step 1330, the Galvanostatic Cycling, Pre-Cycle Stage 3, begins whenPre-Cycle Stage 2 terminates. Start by charging the cell by applying acurrent between 1 uA to 115 uA. Stop the charge cycle when the uppervoltage is between 500 mV and 4.5V, a higher upper voltage cutoff limitthan in Pre-Cycle Stage 2. Discharge the cell by applying a current inthe opposite direction with a magnitude of between 1 uA and 25 uA, withthe applied discharge current being the same or higher magnitude thanthe discharge current applied in Pre-Cycle Stage 2 1320. Stopdischarging the cell at lower voltage between 0.010V to 1V, with thelower voltage cutoff magnitude being the same or higher magnitude thanthe lower voltage cutoff magnitude utilized in Pre-Cycle Stage 2 1320.Stop Pre-Cycle Stage 3 or repeat the Pre-Cycle Stage 3 charge/dischargeschedule up to 20 times.

At this point the active region interface 190 and the SPE have beenelectrochemically transitioned to their final compositions and theenergy storage device 100 is operational.

Step 1340, the Galvanostatic Cycling, the Normal Cycle Stage, beginswhen Pre-Cycle Stage 3 terminates. Begin by charging the cell byapplying a current between 20 uA to 200 uA. Stop the current chargecycle when the upper voltage is between 500 mV and 6V, higher than inPre-Cycle Stage 3. Discharge the cell by applying a current in theopposite direction with a magnitude between 1 uA and 50 uA, with theapplied discharge current being the same or higher magnitude than thedischarge current applied in Pre-Cycle Stage 3 1330. Stop dischargingthe cell when the lower voltage is between 0.010V to 1.0V, with thelower voltage cutoff magnitude being the same or higher magnitude thanthe lower voltage cutoff magnitude utilized in Pre-Cycle Stage 3 1330.Repeat step 1340 charge/discharge schedule as desired and with orwithout alteration of the previously described current/voltage ranges ofstep 1340.

FIG. 14 is a block diagram of one preferred structure 1400 of thepresent battery invention ready for or during operation and aftergalvanostatic current cycling 1300 is applied. The structure 1400comprises a novel composite anode 1475 and novel composite electrolyte1438.

The structure 1400 comprises the trench 150 (trench cavity 158) withinthe substrate 160. The insulating layers (154, 156) and the bi-layer(230, 240) contain the structure 1400 internals, e.g. anode composite1475, electrolyte composite 1438, and cathode 1480, within the trench150. In this non-limiting example embodiment all the structure 1400internals are within the trench 150 (trench cavity 158.)

Exterior electrical connections to the structure 1400 are made through acathode contact 1485 (see description of contact 185) and substratecontact 1499 (see description of contact 199.) Encapsulation (192, 194)casing structures and connections to other micro-battery structures 295to form coin cells or other higher order structures are not shown.

As a result of initial material selection, placement, and structure andthe application of galvanostatic current cycling 1300 as describedabove, movement of materials like Lithium ions, Li+, 1410 and polymers1415 cause dynamic electrochemical and physical changes in situ in thetrench cavity 158 that create new compositions and structures thatresult in the final operation structure 1400. The anode composite 1475and the electrolyte composite 1438 are two of these new compositions andstructures that enable the enhanced performance of the battery structure1400.

During the galvanostatic current cycling 1300, as explained above,Lithium ions initially move due to higher conductive of the selectedmaterials to uniformly and fully saturate the substrate 160 with Lithiumions. As electrons are introduced through the substrate contact 1499 andtaken from the silicon atoms in the substrate 160, the Lithium metallayer 240 and interphase layer 230 start forming. As explained above,the Lithium metal layer 240 eventually inhibits relatively highmagnitudes of Lithium ions from penetrating or leaving the substrate160, particularly the lithiated regions of the substrate 160A. Asdiscussed, the bi-layer (230, 240) helps contain and isolate the batteryinternals so when any mechanical or volume change due tolithiation/de-lithiation of the lithiated substrate 160A or plating andstripping from the Lithium metal layer 240, are well compensated for andhence mechanical stress to the system is relieved—enabling a reversiblysustainable novel energy storage device.

However, due to the initial material selection and placement and thenovel processes of this invention, other materials, e.g. polymers andLi-ions, are moving through the structure 1400 to form the compositeanode 1475 and electrolyte 1438.

As the bi-layer (230, 240) forms, the polymer 170B settles above thelithium metal layer 240 and/or chemically and physically adhered withPANI material to form a novel conductive polymer adhesive layer 1470. Ina preferred embodiment, the conductive polymer adhesive layer 1470contains PANI and the conductive polymers/plasticizers, e.g. SN, thatmigrated from the electrolyte during the formation of the bi-layer (230,240.) The polymers in the conductive polymer adhesive layer 1470 createa high ionic conductive region that reduces the internal resistance ofthe structure 1400 while providing good adhesion between the transformedregion of the central anode structure 1477 and the active region 190.

Together the lithiated substrate 160A, bi-layer (230, 240), and theconductive polymer adhesion layer 1470 comprise an anode transitionlayer bottom 1471 which electrically, chemically, and physicallytransitions from more independently adhered layers (Active Region190+polymer 1470+anode material 1477) to a lower impedance anodecomposite 1475 which is composed of the precursor anode material, e.g.graphite and polymer electrolyte of homogenous unitary construction dueto the electrochemically induced intermixing of the anode material 1477and polymer material 1470 and therefore higher adhesion and lower chargetransferring impedance between the polymer material 1470, bi-layer (230,240) and lithiated substrate 160A to the silicon substrate 160 material.Hence the electrochemical formation of the anode composite 1475, asproduced through the electrochemical pre-cycling steps described in FIG.13 is the key to the reversibly sustainable high charge storageperformance of the In-Silicon energy storage device.

In addition, due to the migration of lithium ions 1410 and polymer 1415the central anode structure 1477 is transformed into a compositestructure of precursor anode material, e.g. graphite, polymer, andlithiated compounds.

Between the central anode structure 1477 and the electrolyte 1430, twotransition layers form: a polymer/electrolyte layer 1425 which is anelectrolyte bottom region 1425 and a polymer/anode/lithium compoundregion 1420 or an anode transition layer top 1420. These two layers alsoform during the galvanostatic current cycling 1300 as selected materialsmove and combine.

The anode transition layer top 1420 comprises precursor anode material,e.g. graphite, and polymers that migrated into the top of the anode fromthe electrolyte 1438. In preferred embodiments, these polymers includepolycaprolactone (PCl) and succinonitrile (SN). Lithium salts, e.g.LiTFSI may also appear in the anode transition layer top 1420. Thecomposition of the anode transition layer top 1420 creates a moreconductive structure which reduces the battery internal resistance. Inconjunction with the electrolyte bottom 1425, the anode transition top1420 creates a strong adhesion between the anode composition 1475 andthe electrolyte composition 1438, thereby even further reducingimpedance due to charge transfer throughout the cell.

As mentioned, due to the selection and placement of materials andstructures and after the galvanostatic current cycling 1300, the anodeis transformed in situ into a anode composite 1475 of several differentregions all chemically connected to one another and chemically andstructurally integrated to form a unified composite—thereby enabling lowimpedance due to desired ion movement through the cell as well as lowresistance to electrical flow to desired areas or materials (e.g.graphite material). The regions of the anode composite 1475 include thelithiated substrate 160A, the interphase 230, the lithium metal layer240 (that grows and shrinks during charge and discharge cycles),conductive polymer adhesion layer 1470, central anode structure 1477,and the anode transition layer top 1420.

In addition, the electrolyte composition 1438 is created comprising theelectrolyte bottom 1425, electrolyte 1430, a separator material (e.g.PAN) and an electrolyte top (above the separator and in contact with thecathode material). The electrolyte 1430 is formed as explained above.However, during current cycling 1300 the polymer (e.g., PCl) and Lithiumconducting (e.g., SN) migrate throughout the cell in, vertically, an upor down direction as current is applied to the full energy storagedevice. Hence the mobility of these SPE components enables a highersaturation of the anode material 1477, thereby further contributing tothe formation of the Anode Composite 1475, yet in addition, theelectrochemical mobility of these materials with Li-ion movementthroughout the cell, creates a well-integrated, void free and lowimpedance regions designated as the electrolyte bottom 1425 and anodetransition layer top 1420—which also contributes greatly to thereversibly sustainable high performance of the In-Silicon energy storagedevice.

A separator layer 1435 is placed between the Electrolyte 1430 and theCathode 1480. In preferred embodiments, the separator 1435 adheres tothe cathode 1480 surface prior to saturating the separator withion-conductive material. Once the separator material is saturated, solidpolymer electrolyte material resides on both the top and bottom sides ofthe separator—thereby contacting the material both above (e.g., cathode)and below (e.g., anode) the separator, where the separator resideswithin the solid polymer electrolyte bulk.

The separator 1435 acts as a dielectric—but, in addition and critically,the separator 1435 is a dielectric which allows for ions (Li-ions) toflow through it 1435, but not electrons. If electrons were able to flowthrough the center region of the cell, then the cell would short circuitand, in the case of Lithium batteries, dendrites may form.

In the present invention, the separator (PAN) is a woven fabric-likepolymer material which is not conductive to electrons. However, becauseit is an interwoven, fabric like material, it can be easily saturatedwith the polymer electrolyte (PCl/SN). This saturation means that thereis complete physical/chemically and therefore ionic transport throughthe separator 1435. In a preferred embodiment, the separator 1435 is apolymer electrolyte saturated separator 1435. In a preferred embodiment,the electrolyte 1430 is a SPE structure, described above, where there ispolymer electrolyte (PCl) above, in the middle of and below theseparator 1435 material.

FIG. 15 is a composite micrograph 1500 showing various regions of thebattery structure 1400 in FIG. 14.

Micrograph 1505 is the lowest magnification micrograph and shows theupper part of entire anode structure 1477 including the upper portion ofthe anode and polymer electrolyte structure region 1510. Region 1510 isshowing a higher magnification of the electrolyte 1430 and theelectrolyte bottom 1425 and anode transition layer top 1420. Micrograph1520 is even a higher magnification showing the electrolyte 1430 and theelectrolyte bottom 1425.

Micrograph 1530 is a high magnification micrograph of the cathodematerial which was in chemical/physical/electrochemical contact with thesubstrate/anode/electrolyte region depicted in 1505 and 1510. Note thatthese micrographs were taken of an In-Silicon energy storage devicefollowing electrochemical charge and discharge cycles. In order todeconstruct the cell and obtain the micrographs of the respective crosssections, the cathode region 1530 had to be separated from thesubstrate/anode/polymer electrolyte regions 1505, 1510. FIG. 15 depictsall of the major components of a post-mortem In-Silicon energy storagedevice, yet in a partially assembled manner. Micrograph 1530 shows theseparator 1435, cathode 1480, and metal cathode contact 1485.

The large arrow 1531 in FIG. 15 illustrates that the separator 1435,cathode 1480, and cathode contact 1485 go on top of the electrolytesurface (the entire electrolyte surface) 1430, which displayed in 1510and 1505—in order to function like a full In-Silicon cell.

The inventions disclosed and the invention specifically claimed in thisdisclosure enable a significant improvement in energy storage devices,compositions, methods, and structures that have use in the IoT sector,microelectronic device sector, CMOS circuit sector and otherapplications. As disclosed, some embodiments have use as miniaturizedenergy storage devices embedded in complementarymetal-oxide-semiconductor (CMOS) circuits or as stand-alonemicrobatteries encapsulated in 3D patterned silicon material orsemiconductor material which can then be integrated with any electronicor microelectronic device. Given this disclosure, one skilled in the artcan envision emerging applications requiring such on-board nextgeneration energy storage devices including IoT devices, mobile devices,sensory equipment, and various autonomous environment, biological,neuromorphic and social functioning machines. Smart dust and biomedicalsensory and drug delivery devices are examples of such functionaldevices. Among other things, these uses are contemplated by thisdisclosure.

It should also be noted that while this invention presently targets themicro and IoT device/application sectors, that the fundamental energystorage device materials and functions (e.g., composite materialsformation, silicon active anode integration, utilizing Silicon forencapsulation of ⅚'s of active battery area) are applicable to other,relatively macro, applications, such as smart phones, electric vehicles,renewable energy storage, grid energy storage, etc.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration but are not intended tobe exhaustive or limited to the embodiments disclosed. Given thisdisclosure, many modifications and variations will be apparent to thoseof ordinary skill in the art without departing from the scope and spiritof the described embodiments. The terminology used herein was chosen tobest explain the principles of the embodiments, the practicalapplication or technical improvement over technologies found in themarketplace, or to enable others of ordinary skill in the art tounderstand the embodiments disclosed herein.

We claim:
 1. A Lithium energy storage device comprising: an electricallyconductive cathode made of a Lithium cathode composition, theelectrically conductive cathode having an external cathode connectionand being capable of producing Lithium ions within the device; acomposite electrolyte having an electrolyte top region, a separator, andan electrolyte bottom region, the electrolyte top region electrically,chemically, and physically transitioning into the cathode, thetransitioning into the cathode being the percentage of the Lithiumcathode composition increasing in locations of the electrolyte topregion nearer to the electrically conductive cathode; a composite anodemade of an anode material, the composite anode having a transition layertop and a transition layer bottom, the transition layer topelectrically, chemically, and physically transitioning into theelectrolyte bottom region; and the transition layer bottom containinggraphite and an electrically and ionically conductive adhesive, thetransition layer bottom that electrically, chemically, and physicallytransitions to and contains a bi-layer, the physical transitioning ofthe transition layer top into the electrolyte bottom region being one ormore polymers that migrated into the transition layer top from theelectrolyte bottom region and the physically transitioning of thetransition layer bottom to the bi-layer being an increase in Lithiummetal in the transition layer bottom in locations in the transitionlayer bottom closer to the bi-layer, the bi-layer comprising: a Lithiummetal layer made of Lithium metal, the Lithium metal layer having aLithium metal layer top and a Lithium metal layer bottom, the Lithiummetal layer top being electrically and physically connected to thetransition layer bottom; and an interphase layer with an interphase topand an interphase bottom, the interphase top electrically and physicallyconnected to the Lithium metal layer bottom; and a lithiated siliconsubstrate with an external electrical connection and the lithiatedsilicon substrate being electrically, chemically and physicallyconnected to the interphase bottom, wherein the interphase layer enableselectrons moving into the interphase layer to combine with the Lithiumions from the cathode to form the Lithium metal in the Lithium metallayer above the interphase top.
 2. A device, as in claim 1, where thelithiated silicon substrate comprises one of the following: a non-poroussilicon, a partially porous crystalline silicon, a single-crystalnon-porous silicon substrate, crystalline silicon, a low resistancedoped crystalline silicon, a boron doped crystalline silicon, or acrystalline silicon material doped with Boron at a concentration ofapproximately 10¹⁹ cm⁻³.
 3. A device, as in claim 1, where the lithiatedsilicon substrate is infused with one or more of: Lithium ions andlithium metal.
 4. A device, as in claim 1, where the concentration ofLithium ions and Lithium metal gradually decreases with distance in thedirection away from the interphase top into the lithiated siliconsubstrate.
 5. A device, as in claim 1, where the interphase layer isless than 35 nm thick.
 6. A device, as in claim 1, where the Lithiummetal layer is uniform thickness and less than 35 nm thick when thedevice is in a discharged state.
 7. A device, as in claim 1, where thetransition layer bottom is made of a uniform mixture of the anodematerial, a Lithium compound, and a conductive adhesive.
 8. A device, asin claim 7, where the percentage composition of the anode materialincreases uniformly in a direction away from the Lithium metal layer andin a direction towards the cathode.
 9. A device, as in claim 7, wherethe anode material is any one or more of the following: graphite,lithiated graphite, activated carbon, carbon and lithium based mixtures,lithium metal, lithium powder/carbon powder composites, lithiumcomposite material saturated in a conductive adhesive mixture, lithiumtitanate material (LTO), silicon/carbon based material,silicon/carbon/additive based material, lithium powder/carbon/solidelectrolyte composite, and a Li-charge hosting anode material.
 10. Adevice, as in claim 7, where the Lithium compound is any one or more ofthe following: a Lithium salt compound, lithium hexafluorophosphate,lithium perchlorate, lithium trifluoromethanesulfonate, lithiumfluoride, lithium bromide, lithium phosphate compounds, lithium bromidecompounds, and Lithium bis(trifluoromethanesulfonyl)imide (LiTFSi). 11.A device, as in claim 7, where the conductive adhesive is any one ormore of the following: polypyrrol, polythiophene, polyaniline (PANI),polyphenylene sulfide, and a conductive adhesive polymer.
 12. A device,as in claim 1, where the transition layer bottom is greater than 100 nmthick.
 13. A device, as in claim 1, where the bi-layer acts as a barrierto inhibit the flow of Lithium ions into and out of the solid siliconsubstrate.
 14. A Lithium energy storage device comprising: anelectrically conductive cathode made of a Lithium cathode composition,the electrically conductive cathode having an external cathodeconnection and being capable of producing Lithium ions within thedevice; a composite electrolyte having an electrolyte top region, aseparator, and an electrolyte bottom region, the electrolyte top regionelectrically, chemically, and physically transitioning into the cathode,the transitioning into the cathode being the percentage of the Lithiumcathode composition increasing in locations of the electrolyte topregion nearer to the electrically conductive cathode; a substrate withone or more trenches, each of the trenches having one or more trenchsides and a trench bottom, the substrate made of lithiated silicon andhaving one or more external electrical contacts and a substrate top; acomposite anode made of an anode material and being within one of thetrenches, the anode material containing graphite, the composite anodehaving a transition layer top and a transition layer bottom, thetransition layer top electrically, chemically, and physicallytransitioning into the electrolyte bottom region and the transitionlayer bottom electrically, chemically, and physically transitioning intoand containing a bi-layer, the physical transitioning of the transitionlayer top into the electrolyte bottom region being one or more polymersthat migrated into the transition layer top from the electrolyte bottomregion and the physical transitioning of the transition layer bottom tothe bi-layer being an increase in Lithium metal in the transition layerbottom in locations in the transition layer bottom closer to thebi-layer, the bi-layer comprising: a Lithium metal layer made of Lithiummetal, the Lithium metal layer having a Lithium metal layer top and aLithium metal layer bottom, the Lithium metal layer top beingelectrically and physically connected to the transition layer bottom;and an interphase layer with an interphase top and an interphase bottom,the interphase top electrically and physically connected to the Lithiummetal layer bottom and the interphase bottom electrically and physicallyconnected to the lithiated silicon substrate at a bottom of the trench,wherein the interphase layer enables electrons moving into theinterphase layer from the substrate to combine with Lithium ions fromthe cathode in order to form the Lithium metal in the Lithium metallayer above the interphase top.
 15. A device, as in claim 14, where oneor more of the trenches is through the substrate top into the substrate,each trench further comprising a trench cavity defined by the bi-layerand the trench sides, a trench depth, and a trench opening with a trenchopening area, the trench further comprising: one or more insulatinglayers covering the trench sides within the trench cavity and coveringthe substrate top forming one or more insulated trench sides and aninsulated substrate top, wherein the insulating layer(s) have beencompletely or partially removed from the trench bottom.
 16. A device, asin claim 15, where the insulating layers comprise one or more of thefollowing: a first layer, a first and second layer, the first layer madeof one of SiO₂ and Si₃N₄, and the second layer made of one of SiO₂ andSi₃N₄.
 17. A device, as in claim 14, where some or all of the compositeelectrolyte is also disposed within the trench.
 18. A device, as inclaim 14, where the Lithium cathode composition comprises one or more ofthe following: Lithium Cobalt Oxide (LCO), lithium manganese oxide(LiMn2O4) (LMO), Lithium Manganese Oxyflouride (Li2MnO2F), lithiumnickel manganese cobalt oxide (LiNiMnCoO2) (NMC), lithium manganesenickel oxide (LiMn1.5Ni0.5O4), lithium iron phosphate (LiFePO4), lithiumiron manganese phosphate (LiFeMnPO4), and lithium nickel cobalt aluminumoxide (LiNiCoAlO2) (NCA).
 19. A Lithium energy storage devicecomprising: an electrically conductive cathode made of a Lithium cathodecomposition, the electrically conductive cathode having an externalcathode connection and being capable of producing Lithium ions withinthe device; a composite Solid Polymer Electrolyte (SPE) having anelectrolyte top interface, a separator layer, and an electrolyte bottominterface, the electrolyte top interface being electrically, chemically,and physically connected to the cathode, the electrolyte top interfaceand the electrolyte bottom interface made of a Lithium compound immersedin the separator layer, the separator layer made of a fiber-wovenmaterial; an anode having and anode top, the anode top beingelectrically, chemically, and physically connected to the electrolytebottom interface, and an anode bottom being a bi-layer comprising: atransition layer with a transition layer bottom; and a Lithium metallayer having a Lithium metal layer top and a Lithium metal layer bottom,the Lithium metal layer top being electrically, chemically, andphysically connected to the transition layer bottom; an interphase withan interphase top and an interphase bottom, the interphase top connectedto the Lithium metal layer bottom; and a solid silicon substrate with anexternal electrical connection and one or more trenches, each trenchhaving a trench bottom, the anode, including the bi-layer, beingdisposed within the trench and the interphase bottom connected to thetrench bottom.
 20. A device, as in claim 19, the thickness of thecomposite SPE is between 28 μm and 82 μm.